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Ab initio calculations on Al2N4 and AlNn (n=4 to 7): potential precursors of high energy density materials

Ab initio calculations on Al2N4 and AlNn (n=4 to 7): potential precursors of high energy density materials
Ab initio calculations on Al2N4 and AlNn (n=4 to 7): potential precursors of high energy density materials
Geometry optimization and harmonic vibrational frequency calculations have been carried out on various structures and low-lying, high- and low-spin electronic states of Al2N4 and AlNn clusters, where n = 4 to 7, at the B3LYP, MP2, and QCISD levels. The aim of these calculations was to search for states/structures that may be suitable candidates as precursors of high energy density materials. Well-bound charge-transfer states/structures with activated NN bonds were obtained. The exothermicities of the decomposition reactions of these states/structures to N2 molecules were computed at up to the RCCSD(T)/aug-cc-pVQZ(no g) level of theory. The most exothermic decomposition reaction considered is AlN6 Cs Al·NN2N2N (N6 ring), 4A' ', (a')1(a')1(a' ')1?Al + 3N2. The calculated ?H298 K is -226 kcal/mol, giving an energy release of over 75 kcal/mol per N2 molecule. We conclude that AlNn systems are potential precursors of high energy density materials. In addition, the HOMOs of these states/structures have been examined in order to understand the stability of these states/structures. The ability of aluminum to introduce various degrees of covalency and ionicity to such clusters, which will stabilize the polynitrogen system, has been discussed.
electronic states, first-principles, excited-state, ground-state, n-7 isomers, clusters, stability, molecules, n-5(+), nitrogen
1089-5639
8680-8695
Lee, Edmond P.F.
f47c6d5d-2d1f-4f03-a3ff-03658812d80b
Dyke, John M.
46393b45-6694-46f3-af20-d7369d26199f
Claridge, Rob P.
559d1b0b-2fdb-4d3f-b439-94b10c808446
Lee, Edmond P.F.
f47c6d5d-2d1f-4f03-a3ff-03658812d80b
Dyke, John M.
46393b45-6694-46f3-af20-d7369d26199f
Claridge, Rob P.
559d1b0b-2fdb-4d3f-b439-94b10c808446

Lee, Edmond P.F., Dyke, John M. and Claridge, Rob P. (2002) Ab initio calculations on Al2N4 and AlNn (n=4 to 7): potential precursors of high energy density materials. Journal of Physical Chemistry A, 106 (37), 8680-8695. (doi:10.1021/jp021059q).

Record type: Article

Abstract

Geometry optimization and harmonic vibrational frequency calculations have been carried out on various structures and low-lying, high- and low-spin electronic states of Al2N4 and AlNn clusters, where n = 4 to 7, at the B3LYP, MP2, and QCISD levels. The aim of these calculations was to search for states/structures that may be suitable candidates as precursors of high energy density materials. Well-bound charge-transfer states/structures with activated NN bonds were obtained. The exothermicities of the decomposition reactions of these states/structures to N2 molecules were computed at up to the RCCSD(T)/aug-cc-pVQZ(no g) level of theory. The most exothermic decomposition reaction considered is AlN6 Cs Al·NN2N2N (N6 ring), 4A' ', (a')1(a')1(a' ')1?Al + 3N2. The calculated ?H298 K is -226 kcal/mol, giving an energy release of over 75 kcal/mol per N2 molecule. We conclude that AlNn systems are potential precursors of high energy density materials. In addition, the HOMOs of these states/structures have been examined in order to understand the stability of these states/structures. The ability of aluminum to introduce various degrees of covalency and ionicity to such clusters, which will stabilize the polynitrogen system, has been discussed.

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More information

Published date: 19 September 2002
Keywords: electronic states, first-principles, excited-state, ground-state, n-7 isomers, clusters, stability, molecules, n-5(+), nitrogen

Identifiers

Local EPrints ID: 19793
URI: http://eprints.soton.ac.uk/id/eprint/19793
ISSN: 1089-5639
PURE UUID: a58b3e05-80f6-4892-93fc-62ae6217b3a7
ORCID for John M. Dyke: ORCID iD orcid.org/0000-0002-9808-303X

Catalogue record

Date deposited: 21 Feb 2006
Last modified: 09 Jan 2022 02:35

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Contributors

Author: Edmond P.F. Lee
Author: John M. Dyke ORCID iD
Author: Rob P. Claridge

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