| Detonation Initiation and Sensitivity in Energetic Compounds: Some Computational Treatments |
08 JUN 1999 |
18 pages |
| Authors:
Peter Politzer; Howard E. Alper; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
 | The initiation of detonation in an energetic compound, and its sensitivity to external stimuli, involves a complicated interaction of such determinants as molecular structure, crystal properties and physical state. There have been numerous computational analyses of the roles of the first two ofthese factors. Molecular dynamics techniques have been used extensively to simulate the initiation and propagation of detonation in model lattices, as wellas to study processes (e.g., energy transfer) ... |
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| Density Functional Calculations of Solid State Heats of Formation |
08 JUN 1999 |
17 pages |
| Authors:
Peter Politzer; M. E. Grice; Jane S. Murray; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| It is now feasible to compute quite accurate gas phase heats of formation for relatively small molecules by means of ab initio or density functional techniques and one of several possible approaches: formation reactions, atomization processes or isodesmic reactions. For larger molecules, some empirical correction terms are necessary, even when using density functional methods. Conversion of gas phase values to liquid and/or solid state heats of formation can be done ... |
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| Conformational Dependence of Molecular Surface Electrostatic Potentials |
08 JUN 1999 |
15 pages |
| Authors:
Jane S. Murray; Zenaida Peralta-Inga; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| In a series of earlier studies, we have shown that a variety of solution, liquid and solid phase properties can be represented analytically in terms of quantities related to the electrostatic potentials on molecular surfaces. These quantities include the positive and negative extrema, the positive and negative average values and variances, and the average deviation. We have now investigated how sensitive these quantities are to the molecular conformation. Surface potentials ... |
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| Cyclooligomerizations as Possible Routes to Cubane-Like Systems |
08 JUN 1999 |
24 pages |
| Authors:
Peter Politzer; Pat Lane; John J. Wiener; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Octanitrocubane and 1,3,5,7-tetranitro-2,4,6,8-tetraazacubane are predicted to be high-performance energetic materials; however neither compound has as yet been synthesized. In principle, they could be prepared by the cyclooligomerizations of dinitroacetylene and nitryl cyanide, respectively. There is some encouraging chemical evidence that this may be feasible. The firststeps in these processes might conceivably be cyclic dimerizations to form tetranitrocyclo-butadiene and 1,3-dinitro-2,4-diazacyclobutadiene. We have used a density functional computational procedure, B3P86/6-31G(**), to analyze ... |
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| Computational Investigation of the Stabilities of Some Proposed Molecules and Molecular-Anions |
22 MAY 1998 |
5 pages |
| Authors:
Peter Politzer; Monica C. Concha; Pat Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Density functional computational studies have shown that molecular structures from 1 to 6 do correspond to energy minima. Their calculated bond lengths are presented and discussed. |
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| A Comparative Analysis of Hartree-Fock and Kohn-Sham Orbital Energies |
27 APR 1998 |
15 pages |
| Authors:
Peter Politzer; Fakher Abu-Awwad; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Hartree-Fock and Kohn-Sham orbital energies, the latter computed with several different exchange correlation functionals are compared and analyzed for twelve molecules. The Kohn-Sham energies differ significantly from experimental ionization energies, but by amounts that are, for a given molecule and exchange correlation functional, roughly the same for all of the valence orbitals. With the exchange correlation functionals used, the energy of the highest occupied Kohn-Sham orbital does not approximate the ... |
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| Some Approximate Kohn-Sham Molecular Energy Formulas |
27 APR 98 |
20 pages |
| Authors:
Peter Politzer; Fakher Abu-Awwad; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Density functional calculations have been carried out for twelve molecules by several different Kohn-Sham procedures in order to test the effectiveness of two approximate molecular energy formulas that have been applied earlier in the context of Hartree-Fock theory. The equation E(molecular) = 3/7( (Vne + 2Vnn), in which Vne and Vnn are the nuclear-electronic attraction and nuclear repulsion, reproduces Kohn-Sham energies with an average deviation of less than 0.70%. E(molecular) ... |
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| Computational Investigation of the Structures and Relative Stabilities of Amino/Nitro Derivatives of Ethylene |
27 APR 98 |
19 pages |
| Authors:
P. Politzer; M. C. Concha; M. E. Grice; J. S. Murray; P. Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Eight amino and/or nitro derivatives of ethylene have been investigated computationally at the density functional B3P86/6-31+G** level. The molecular geometries and relative stabilities reflect the varying roles of "push-pull" electronic delocalization and intramolecular hydrogen bonding. The same two factors affect, to varying extents, the computed C-NO2 and C-NH2 bond dissociation energies, which are also presented, as are the heats of formation, vaporization and sublimation of the three diaminodinitroethylenes. The potential ... |
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| Some Chemical and Structural Factors Related to the Metastabilities of Energetic Compounds |
27 APR 98 |
19 pages |
| Authors:
Peter Politzer; Jane S. Murray; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| We have presented an overview of various attempts to relate the impact and shock sensitivities of energetic materials to their molecular structures. The objectives of such efforts are to better understand the chemical and structural determinants of these sensitivities, and to develop a predictive capability to facilitate the evaluation of new and proposed energetic compounds. Our particular emphasis in this discussion has been upon the relationship of impact sensitivities to ... |
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| The Molecular Electrostatic Potential: A Tool for Understanding and Predicting Molecular Interaction |
27 APR 98 |
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| Authors:
Judah Goldwasser; Jane S. Murray; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
 | The use of the electrostatic potential in analyzing and predicting molecular interactive behavior and properties has increased remarkably over the past 25 years. In 1980, it was still reasonable to hope to at least mention, in one lengthy review chapter, all of the papers that had been published in this area. In 1996, such an objective would be ridiculous. This popularity can be attributed to (a) the insight that V(r) ... |
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| Computed Heats of Formation |
09 APR 98 |
5 pages |
| Authors:
Peter Politzer; M. E. Grice; Monica C. Concha; Pat Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| We have computed heats of formation for compounds 1 - 8 (Table 1). The first five are target compounds proposed by M. Trudell (University of New Orleans); 6 - 8 have recently been prepared by R. Schmitt and J. Bottaro (SRI). For the molecular systems 1 - 7, we used our density functional procedure to obtain gas phase heats of formation, which were converted to liquid and solid state values ... |
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| Computed Properties of 1 ,1-Diamino-2,2-Dinitroethylene |
15 AUG 97 |
9 pages |
| Authors:
Peter Politzer; M. E. Grice; Monica C. Concha; Pat Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| For 1,1-diamino-2,2-dinitroethylene, (H2N)2C=C(NO2)2, computational techniques have been used to predict its solid, liquid and gas phase heats of formation, its heats of vaporization and sublimation, its specific impulse, the C-NO2 and C-NH2 bond strengths, and its molecular geometry. There is significant intramolecular hydrogen bonding as well as electron delocalization, both of which stabilize the molecule and increase the C-NO2 and C-NH2 dissociation energies; this is expected to diminish the compound's ... |
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| Computed Heats of Formation |
13 AUG 1997 |
4 pages |
| Authors:
Peter Politzer; M. E. Grice; Pat Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Computed heats of formation for 1-4. We have used our density functional procedure 1 to compute the heats of formation of the compounds 1 - 4, in response to a request from R. Naylor (Allegany Ballistics Laboratory). The vibrational energies were determined from the molecular stoichiometries 2. The density functional calculations give the gas phase heat of formation, which we convert to the liquid and solid state values by subtracting, ... |
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| Computed Heats of Formation of Three Diazapentalenes, and Two Gem- Dinitro/Gem-Difluoramino Analogues of RDX |
24 JAN 97 |
4 pages |
| Authors:
Peter Politzer; M. E. Grice; Jane S. Murray; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| We have used our density functional procedure 1 to compute the heats of formation of the compounds 1 - 5. 1 and 2 have been prepared by R. Schmitt and J. Bottaro at SRI and 3 is under consideration. The syntheses of 4 and 5 are being pursued by T. Axenrod (CUNY). The vibrational energies were determined from the molecular stoichiometries 2. The density functional calculations give the gas phase ... |
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| Computed Heats of Formation of Three Tetraazapentalenes, A tris(Nitrotriazolo)Triazine, and a Tricyclic Gem-Difluor-Amino/Tetranitramine |
14 NOV 96 |
4 pages |
| Authors:
Peter Politzer; M. E. Grice; Jane S. Murray; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Computed heats of formation for 1 - 5. We have used our density functional procedure to compute the heats of formation of the compounds 1 - 5, proposed by W. Koppes and A. Stern (ONR). The vibrational energies were determined from the molecular stoichiometries. The density functional calculations give the gas phase heat of formation, which we convert to the solid state value by subtracting the heat of sublimation. The ... |
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| Synthesis and Structure of 4-(4-Nitro-1,2,5-Oxadiazol-3- y1) -NNO- azoxyl-1,2,5-Oxadiazol-3-Amine |
30 OCT 96 |
16 pages |
| Authors:
Alexander K. Zelenin; Edwin D. Stevens; Mark L. Trudell; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
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| The synthesis of the energetic compound 4-(4-NITRO-1,2,5-OXADIAZOL-3- YL)-NNO-azoxyl-1,2,5-oxadiazol-3-amine (3) was achieved in two steps from diaminofurazan (1). Compound 3 was characterized by X-ray diffraction. From the X-ray structure a bifurcated intramolecular H-bond between O(2)- H(2)- N(4) was observed. In addition, intramolecular H-bonding was observed between H(1) and N(7) of an adjacent molecule. One molecule of ethanol and one-half molecule of water per molecule of water of 3 was observed in ... |
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| Synthesis of Benzotriazolo 1, 2-A Benzotriazole Derivatives as New High Density, Insensitive Energetic Materials |
25 JUL 96 |
15 pages |
| Authors:
Ganesan Subramabian; Genevieve Eck; Joseph H. Boyer; Edwin D. Stevens; Mark L. Trudell; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| The synthesis of the new high density energetic compound 4,8-dinitro- 12H- 1,2,5 oxadiazolo3,4-E 1,2,5 oxadiazolo3',4':4,5benzotriazolo 1 ,2- Abenzotriazol-13-ium inner salt 1,11-dioxide (7) was achieved in three steps (37% yield) from 2,4,8,10- tetranitrobenzotriazolo1 ,2-Abenzotriazolo-6-ium inner salt (4). The compound 7 was found to be thermally stable up to 274 deg C and was insensitive to impact (hammer/anvil test). p1 |
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| Density Functional Investigation of Some Decomposition Routes of Methyl Nitrate |
05 JUL 96 |
10 pages |
| Authors:
Herman Krier; M. Q. Brewster; Peter Politzer; Jorge M. Seminario; M. C. Concha; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Two density functional methods, B3/LYP/6-31+G(d) and B3/PW91/6-31G(d, p) have been used to investigate some possible decomposition pathways for methyl nitrate. Two likely ones were found to be (a) loss of NO2, followed by eventual rearrangement to H2C-OH, and (b) formation of H2C=O and HONO. The initial energy requirement for each process is about 40 kcal/mole, and the second is exothermic, delta H = -16 kcal/mole of H3CO-NO2. The B3/LYP procedure ... |
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| Energetics of HF Elimination and N-F Bond Cleavage in Some Difluoramines and Gem-Nitro/Difluoramines |
05 JUL 96 |
9 pages |
| Authors:
Peter Politzer; Pat Lane; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| We have shown, through density functional calculations (Becke exchange/Lee, Yang and Parr correlation functionals, 6-31G** basis set) that the elimination of HF from H3C-NF2 is thermodynamically favored, Delta G(298.15 K) = -29 kcal/mole, but has a relatively high activation barrier, Delta G(double dagger)(298.15 K) = 38 kcal/mole. The N-F dissociation energy, Delta E sub(N-F), is found to be 69 kcal/mole. Introduction of a nitro group, giving H2C(NO2)NF2, produces only small ... |
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| Some Computationally-Predicted Properties of a Group of Proposed Energetic Compounds |
JUN 96 |
6 pages |
| Authors:
Peter Politzer; Pat Lane; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| We have carried out computational analyses and predictions of certain properties for a group of proposed energetic target compounds. The properties reported are: Heat of formation, 298 K, gaseous; heat of sublimation, 298 K; heat of formation, 298 K, solid; heat of fusion at melting point; heat of vaporization at boiling point; density, liquid; boiling point; impact sensitivity. Of the molecules considered, 1,3,5,7-tetranitro-2,4,6,8- tetraazacubane is particularly promising as a potential ... |
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| Computed Heats of Formation of Difluoramine Analogues of RDX and HMX |
JUN 96 |
4 pages |
| Authors:
Peter Politzer; M. E. Grice; Pat Lane; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| We have used our density functional procedure (1) to compute the heats of formation of three difluoramine analogues of RDX and HMX, 1 - 3. The vibrational energies were determined from the molecular stoichiometries (2). The density functional calculations give the gas phase heat of formation, which we convert to the solid state value by subtracting the heat of sublimation. We obtain the latter by means of the relationship that ... |
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| Synthesis of 2,6-Diethyl-3-Methacroyloxymethyl-1,5,7,8- Tetramethylpyrromethene-BF2 for the Preparation of New Solid-State Laser Dyes |
26 APR 96 |
15 pages |
| Authors:
Tonghua Chen; Joseph H. Boyer; Mark L. Trudell; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| The synthesis of 2,6-diethyl-3-methacroyloxymethyl- 1 ,5,7,8- tetramethylpyrromethene- BF2 (2) was prepared in straight forward fashion from 2,6-diethyl-1,3,5,7,8-pentamethylpyrromethene-BF2 (1) in three steps. The monomer unit 2 has been shown to be useful for copolymerization with methyl methacrylate for the synthesis of new solid-state optical materials. In addition, the synthesis of 1 has been modified to give greater yields of this useful laser dye. |
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| Computed Heat of Formation and Impact Sensitivity of a New Dinitro-N- fluorotriazole |
07 MAR 96 |
3 pages |
| Authors:
Peter Politzer; J. S. Murray; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| The dinitro-N-fluorotriazole 1 has recently been synthesized 1 and characterized crystallographically 2. We now report our computed heat of formation and impact sensitivity for 1. The gas phase heat of formation was calculated using our density functional procedure 3. It was converted to the solid phase value by means of eq. (1), delta H(sub f) (solid) = delta H(sub f) (gaseous) - delta Hsub (1) in which delta Hsub is ... |
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| Relationships Between Dissociation Energies and Electrostatic Potentials of C-NO2 Bonds. Applications to Impact Sensitivities. |
25 JAN 1996 |
13 pages |
| Authors:
Peter Politzer; Jane S. Murray; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| New data for nitroalkanes support earlier results lor nitroheterocycles indicating that C-NO2 dissociation energies are related to the computed electrostatic potential maxima on the molecular surfaces above these bond regions. This presumably explains the well-established involvement of the electrostatic potential in impact sensitivity correlations; a second factor in the latter, for unsaturated systems, is the internal charge separation in the molecule. jg p1 |
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| Computational Determination of Heats of Formation of Energetic Compounds. |
25 JAN 1996 |
14 pages |
| Authors:
Peter Politzer; Jane S. Murray; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A recently-developed density functional procedure for computing gas phase heats of formation is briefly described and results for several categories of energetic compounds are summarized and discussed. Liquid and solid phase values can be obtained by combining the gas phase data with heats of vaporization and sublimation estimated by means of other relationships. Some observed functional group effects upon heats of formation are noted. jg p1 |
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| Structures and Molecular Surface Electrostatic Potentials of High Density C, N, H Systems. |
25 JAN 1996 |
19 pages |
| Authors:
Jane S. Murray; Richard Gildardi; M. E. Grice; Pat Lane; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Tri-s-triazine and two ditetrazolodiazines are known to have unusually high crystal densities (for unsubstituted C, N, H compounds). We have used a nonlocal density functional procedure to compute the geometries and energies of these and three related molecules, and then calculated the ab initio SCF electrostatic potentials on their molecular surfaces. We attribute the high densities to the relatively small molecular volumes and the strong intermolecular attractions arising from highly ... |
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| Molecular Electrostatic Potentials as Indicators of Covalent Radii. |
25 JAN 1996 |
10 pages |
| Authors:
John J. Wiener; M. E. Grice; Jane S. Murray; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Through nonlocal density functional calculations (B/LYP/6 -31C**), we show that the minimum of the molecular electrostatic potential along an internuclear axis provides a more realistic boundary point between two bonded atoms than does the electronic density minimum. We also suggest that the two bonded atoms contribute approximately equally to the magnitude of the minimum potential along the axis. |
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| Predicted Heats of Formation of DNAF in Gaseous, Liquid and Solid Phases. |
10 OCT 1995 |
3 pages |
| Authors:
Peter Politzer; Jane S. Murray; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| One of the compounds for which we have recently computed the gas phase heats of formation, delta H sub f gaseous), is DNAF, 1 (1). This was done using our density functional procedure (2). In response to interest expressed by the Air Force Armament Laboratory (Eglin AFB), we have now estimated the liquid and solid phase heats of formation of 1. For this purpose, we needed the heats of vaporization, ... |
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| Heats of Formation, Structures and Relative Stabilities of Some Tetraazapentalene-Related Molecules |
20 JUN 95 |
12 pages |
| Authors:
M. E. Grice; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A density functional procedure has been used to compute gas phase heats of formation for a group of high nitrogen molecules, primarily tetraazapentalene derivatives. Optimized structures and relative energies were computed for the key molecular framework and several isomeric forms. It is speculated that the unexpected tetraazapentalene stability that is observed experimentally is related to the relatively positive character of the triply- coordinated nitrogens. jg |
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| Reactions of Benzotriazolo(2,1-alpha)benzotriazole Derivatives. I. Synthesis of New Insensitive High Density Energetic Compounds |
03 MAY 95 |
26 pages |
| Authors:
Ganesan Subramanian; Joseph H. Boyer; Dan Buzatu; Edwin D. Stevens; Mark L. Trudell; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| The sequential preference of electrophilic attack on the dibenzotetraazapentalene ring system 6 has unequivocally been shown to be in the order of position 2(8) > 4(10) >> 1(7) and 3(9). However, nucleophilic substitution reactions with sodium azide were found to be substrate dependent. Substitution occurred at the 3(9)-position of 9 followed by elimination of hydrogen chloride to give 10 while direct substitution of azide for the 4(10)- nitro group of ... |
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| A Density Functional Analysis of a Decomposition of 4-Nitro-1,2,3- Triazole through the Evolution of N2 |
20 MAR 95 |
9 pages |
| Authors:
Peter Politzer; M. E. Grice; Jorge M. Seminario; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A density functional computational study shows that 4-nitro- 1,2,3- triazole, which is highly impact sensitive, can decompose through ring opening and subsequent N2 evolution, with the net release of 12 kcal/mole. An input of 52 kcal/mole is required to initiate the process. jg |
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| C-NO2 Dissociation Energies and Surface Electrostatic Potential Maxima in Relation to the Impact Sensitivities of Some Nitroheterocyclic Molecules |
20 MAR 95 |
9 pages |
| Authors:
Peter Politzer; Jane S. Murray; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A nonlocal density functional procedure (GAUSSIAN 92/DFT, BLYP, 6- 31G) has been used to compute the dissociation energies of the C-NO2 bonds in five unsaturated nitroheterocyclic molecules. These show a definite correlation with the maxima of the surface electrostatic potentials above these bonds, which may explaln why these potential maxima are one of the properties that appear in an earlier analytical representation of the measured impact sensitivities of nitroheterocyclic compounds. ... |
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| Computational Investigation of the Stabilities of Some N, O, F Ions |
16 MAR 95 |
4 pages |
| Authors:
M. E. Grice; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| In response to the suggestion of Jeff Bottaro, we have investigated the potential stabilities of four N, 0, F ions, 1 - 4. All four molecular geometries were optimized using a non-local density functional (DF) procedure (Gaussian 92/DEF; BLYP6/-31+G**) and also at the ab initio MP2/6-31+G** (frozen core) level. For 1, the MP optimization was carried out as well without the frozen- core approximation. All calculations were for spin-restricted singlet ... |
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| A Convenient Synthesis of Diaminoglyoxime and Diaminofurazan: Useful Precursors for the Synthesis of High Density Energetic Materials |
08 MAR 95 |
10 pages |
| Authors:
Ananthakrishnan Gunasekaran; Thiruvalam Jayachandran; Joseph H. Boyer; Mark L. Trudell; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| The reaction of glyoxime (4) and hydroxylamine hydrochloride in aqueous sodium hydroxide was found to be a safe and inexpensive method for the preparation of multigram quantities of diaminoglyoxime (5). Potassium hydroxide mediated dehydration of 5 furnished diaminofurazan (1) in good yield of exceptional purity. The ready availability of 1 and 5 has facilitated the synthesis of new energetic furazan derivative MNOTO (B). jg |
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| Analysis of Factors Affecting Chemical Reactions in Supercritical Fluids |
03 FEB 95 |
|
| Authors:
Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Our objectives in this project have been to achieve a better fundamental understanding of supercritical fluids, particularly their solvent powers and the mechanisms by which influence the rates and equilibria of chemical reactions, and to develop data and a predictive capability for the controlled oxidations in supercritical fluids of chemical defense agents. We have developed a General Interaction Properties Function (GIPF) based on molecular surface properties (primarily the surface electrostatic ... |
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| A Density Functional/Molecular Dynamics Study of the Structure of Liquid Nitromethane |
20 DEC 94 |
8 pages |
| Authors:
Jorge M. Seminario; Monica C. Concha; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A molecular dynamics simulation of liquid nitromethane has been carried out in which a density functional (DF) procedure was used to compute the properties needed to establish the intermolecular force field. The latter was subsequently updated by further DF calculations. The first and second shells of neighbors are found to be at radii of about 6 A and 11 A from a given nitromethane molecule. OH partial pair correlation functions ... |
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| Continued Computational Evaluation of the Feasibility of Nitrating Precursors to C (12)N (12)O(12) |
05 DEC 94 |
4 pages |
| Authors:
Peter Politzeer; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Extending the work reported in Technical Report No. 71 (October 20, 1994), we computed the average local ionization energies on the surfaces of two more possible precursors to 1. No minima were found at the positions to be nitrated, indicating that these are not favored sites for this purpose. |
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| Density Functional Studies of Decomposition Processes of Energetic Molecules |
03 NOV 94 |
13 pages |
| Authors:
Peter Politzer; Jorge M. Seminario; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Nonlocal density functional theory is an effective means for determining the energetics and elucidating the mechanisms of the decomposition processes of molecules of real chemical interest and significance. It should be viewed as another practical tool that is available for this purpose, a useful addition to existing experimental techniques, but with the extremely important advantage that it can be applied to proposed molecules that may not yet have been synthesized ... |
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| Comparative Computational Analysis of Some Nitramine and Difluoramine Structures, Dissociation Energies and Heats of Formation |
03 NOV 94 |
12 pages |
| Authors:
Peter Politzer; Pat Lane; M. E. Grice; Monica C. Concha; Paul C. Redfern; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Density functional methods have been used to compute the optimized geometries, dissociation energies and gas phase heats of formation of several difluoramines (in which the -NF2 is attached to a nitrogen) and the corresponding nitramines. The -NF2 groups are found to be pyramidal, in contrast to the planarity of the -NO2. In each instance, one N-F bond length is at least 0. 1 A longer than the other, while the ... |
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| Non-Local Density Functional Calculations of Gas Phase Heats of Formation |
03 NOV 94 |
11 pages |
| Authors:
Dariush Habibollahzadeh; M. E. Grice; Monica G. Concha; Jane S. Murray; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A general procedure is presented for computing the gas phase heats of formation of a wide variety of organic compounds. Delta E for the formation. of the molecule from its elements at O deg K is obtained from density functional calculations (Gaussian 92/DFT) for optimized geometries. This result is converted to delta H at 298 deg K by assuming ideal behavior and adding the translational, rotational and vibrational energies. Additive ... |
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| Calculated Heats of Formation of Some Predicted Stable C, N, O, F molecules |
20 OCT 94 |
|
| Authors:
Peter Politzer; Pat Lane; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| 21 POTENTIAL ENERGETIC MOLECULES, CONTAINING ONLY C, N, 0, F, were found to have true local energy minimal at the Hartree-Fock 6-31G* computational level. A density functional procedure was used to find their gas phase heats of formation. The nitros group significantly increases Delta H sub f compared to the nitro analogue, while NF2 decreases it. C, N, 0, F Molecules, Stability, Heat of formation, Computational study. |
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| Computational Evaluation of the Feasibility of Nitrating Precursors to C12N12O12 |
20 OCT 94 |
7 pages |
| Authors:
Peter Politzer; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| In order to determine the feasibility of nitrating the immediate precursors of 1, we have computed the average local ionization energies on their surfaces and compared their minimum values to those of mono-, di- and trinitrobenzene. Our results indicate that there is a reasonable likelihood of being able to nitrate the precursors of 1. C12N12O12, Nitration, Average local ionization energies |
|
| Computational Studies in Support of Energetic Materials Synthesis |
30 SEP 94 |
16 pages |
| Authors:
Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
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| Investigation of Anomalous Predicted Bond Lengths in some 1 ,1- Difluorohydrazines |
20 MAR 94 |
9 pages |
| Authors:
Peter Politzer; M. E. Grice; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| Bond length anomalies found in some 1,1-difluorohydrazines are conformation-dependent and are absent in the presence of strongly electron- attracting substituents, supporting their interpretation in terms of charge delocalization. jg |
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| Molecular Dynamics Simulation of Liquid Nitromethane Shocked to 143 Kbar |
20 MAR 94 |
10 pages |
| Authors:
Jorge M. Seminario; Monica C. Concha; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
|
| A molecular dynamics simulation, using a force field established by density functional calculations, has been used to investigate structural and vibrational frequency shifts that accompany a compression from 1 bar, 300 K to 143 kbar, 600 K. Under the latter conditions, most pairs of nitromethane molecules are found to be linked by two hydrogen bonds, instead of the one that is observed at 1 bar, 300 K. The computed shifts ... |
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| Computational Study of the Structure of Dinitraminic Acid, HN(NO2)2, and the Energetics of Some Possible Decomposition Steps |
27 DEC 93 |
11 pages |
| Authors:
Peter Politzer; Jorge M. Seminario; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
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| MP2/6-3 1 G* geometry optimizations combined with non-local density functional energy calculations were used to determine the structure of dinitraminic acid, HN(NO2)2, and the energetics of several processes that may be involved in its decomposition. These include bond cleavage and also fragmentation induced by protonation. Density functional theory, Protonation, Dinitraminic acid, Bond-cleavage, Fragmentation. |
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| Molecular Surface Electrostatic Potentials in the Analysis of Non- Hydrogen-Bonding Noncovalent Interactions |
27 DEC 93 |
16 pages |
| Authors:
Jane S. Murray; Kim Paulsen; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
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| Electrostatic potentials computed on molecular surfaces are used to analyze some noncovalent interactions that are not in the category of hydrogen bonding, e.g. halogen bonding . The systems examined include halogenated methanes, substituted benzenes, s-tetrazine and 1,3-bisphenylurea. The data were obtained by ab initio SCF calculations. Electrostatic potentials, Non-hydrogen- bonding noncovalent interactions, Molecular surfaces |
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| Does Antiaromaticity Imply Destabilization? |
27 DEC 93 |
9 pages |
| Authors:
Jane S. Murray; Jorge M. Seminario; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
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| An analysis is presented of the results of earlier ab initio computational studies of cyclobutadiene, cyclooctatetraene and 1,4- dihydropyrazine. The first and third of these are normally categorized as antiaromatic. All three molecules are polyenes, even when the last two are forced into planar conformations. There is no driving. force for extensive pi delocalization, even when it would appear to have been facilitated. Calculated isodesmic energies show a net destabilization ... |
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| Calculated Structure, Heats of Formation and Decomposition Energetics of 1,3-Dinitro,-1,3-Diazacyclobutane |
27 DEC 93 |
8 pages |
| Authors:
M. E. Grice; Dariush Habibollahzadeh; Peter Politzer; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
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| Using HF/6-31G* optimized geometries, the heat of formation of 1,3- dinitro-1,3-diazacyclobutane and the energetics of two possible decomposition reactions were computed by a non-local density functional procedure (deMon). Delta H f at 25 deg C is 351 cal/g; the N-NO2 dissociation energy is 36.6 kcal/ mole, and the activation barrier for symmetrical ring fragmentation is 44.2 kcal/mole. Heats of formation, 1,3-Dinitro-1,3-diazacyclobutane, Decomposition reactions, Non-local density functional procedure |
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| Antiaromaticity in Relation to 1,3,5,7-Cyclooctatetraene Structures |
27 DEC 93 |
8 pages |
| Authors:
Peter Politzer; Jane S. Murray; Jorge M. Seminario; NEW ORLEANS UNIV LA DEPT OF CHEMISTRY
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| An isodesmic energy analysis has been carried out at the MP2/6-31G*// HF/3-21G level for the non-planar ground state (1) of 1,3,5,7-cyclooctatetraene and for two planar forms, one having complete pi delocalization (2) and the other having alternating single and double bonds (3). 1 is found to have a considerable degree of stabilization, which is attributed to limited pi delocalization. The polyene 3 is the more stable of the two planar ... |
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