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Douglas L Strout

Publications and source records attributed to Douglas L Strout.

10 recordsLinked to original sources
PubMed2006

Isomer stability and bond-breaking energies of N8C8H8 cages.

Molecules consisting entirely or predominantly of nitrogen have been extensively investigated for their potential as high-energy density materials (HEDM). Such molecules react to produce N2 and large amounts of energy, but many such molecules are too unstable for practical applications. In the present study, cage isomers of N8C8H8 are studied using theoretical calculations to determine the structural features that lead to the most stable cages and determine the energetics of dissociation for the various isomers. The isomers are evaluated for thermodynamic (isomer vs isomer) stability and kinetic (with respect to dissociation) stability. Density functional theory (B3LYP), perturbation theory (MP2), and coupled-cluster theory [CCSD(T)] are employed, in conjunction with the cc-pVDZ basis set of Dunning. Trends in isomer stability and dissociation energies are calculated and discussed.

Algorithms↗
PubMed2006

Stability of high-energy N14H4(2+) ion and the effects of carbon and halogen substitution.

Previous studies of oxygen addition into an N12 cage framework revealed the possibility of stable high-energy density materials (HEDM) resulting from such additions. In the current study, nitrogen addition into N12 is studied as a means of generating stable HEDM. Nitrogen addition into N12 is shown to yield an N14H4(2+) ion, which is examined by theoretical calculations to determine its stability with respect to dissociation. Other variations on this ion are generated by substituting carbon for nitrogen and/or halogens for hydrogen. The cage structures will be compared with respect to stability, and factors that enhance stability will be discussed.

Carbon↗
PubMed2006

Isomer stability of N6C6H6 cages.

Recent theoretical studies have identified carbon-nitrogen cages that are potentially stable high energy density materials (HEDM). One such molecule is an N(6)C(6)H(6) cage in which a six-membered ring of nitrogen is bonded to C(3)H(3) triangles on both sides. This molecule is based on the structure of the most stable N(12) cage, with six carbon atoms substituted into the structure. In the current study, several N(6)C(6)H(6) isomers (including the previously studied cage) are examined by theoretical calculations to determine which is actually the most stable. Stability will be evaluated from two points of view: (1) thermodynamic stability of one isomer versus another and (2) kinetic stability of each isomer as determined by the energetics of bond breaking. Density functional theory (B3LYP), perturbation theory (MP2 and MP4), and coupled-cluster theory (CCSD(T)) are used in this study, along with the correlation-consistent basis sets of Dunning. Trends in thermodynamic and kinetic stability are discussed.

Carbon↗
PubMed2006

Boron nitride cages from B12N12 to B36N36: square-hexagon alternants vs boron nitride tubes.

The structures and stabilities of square-hexagon alternant boron nitrides (Bx Nx , x=12-36) vs their tube isomers containing octagons, decagons and dodecagons have been computed at the B3LYP density functional level of theory with the correlation-consistent cc-pVDZ basis set of Dunning. It is found that octagonal B20N20 and B24N24 tube structures are more stable than their square-hexagon alternants by 18.6 and 2.4 kcal mol(-1), respectively, while the square-hexagon alternants of other cages are more stable. Trends in stability as a function of cluster size are discussed.

Boron Compounds↗
PubMed2006

Stability of carbon-nitrogen cages in fourfold symmetry.

Molecules consisting entirely of nitrogen have been studied extensively for their potential as high-energy density materials (HEDM). Many nitrogen molecules previously studied have low-energy dissociation routes and are therefore too unstable to serve as practical HEDM. However, the incorporation of heteroatoms into a nitrogen structure can have stabilizing effects. Theoretical calculations are carried out on a sequence of high-energy cages with carbon and nitrogen. Density functional theory (B3LYP), perturbation theory (MP2 and MP4), and coupled-cluster theory (CCSD(T)) are used in conjunction with the correlation-consistent basis sets of Dunning. Stability trends as a function of molecule size are calculated and discussed.

Azides↗
PubMed2005

The structure and stability of B36N36 cages: a computational study.

The structure and stability of 22 B36N36 cage molecules containing four-membered (F4), five-membered (F5), six-membered (F6), eight-membered (F8) and 12-membered (F12) rings have been computed at the B3LYP/6-31G* level of density functional theory. The most stable structure (1) has T(d) symmetry with six F4 and 32 F6 rings, following the isolated square rule, while the fullerene-like structures (12 F5 and 26 F6) and also structures with F8 and F12 are much higher in energy. Figure The T(d) symmetrical structure (1) with six F4 and thirty-two F6 rings is the most stable B36N36 cage.

Carbon↗
PubMed2005

Stability of nitrogen-oxygen cages N12O2, N14O2, N14O3, and N16O4.

Molecules consisting entirely of nitrogen have been studied extensively for their potential as high energy density materials (HEDM). However, many such molecules are too unstable to serve as practical energy sources. This has prompted many studies of molecules that are mostly nitrogen but which incorporate heteroatoms into the structure to provide additional stability. In the current study, cages of three-coordinate nitrogen are viewed as candidates for stabilization by insertion of oxygen atoms into the nitrogen framework. Cages of N12, N14, and N16 with four-membered rings are studied because four-membered rings have been previously shown to be a destabilizing influence. Insertion of oxygen atoms, which converts N-N bonds to N-O-N bonding groups, relieves ring strain and can potentially result in stable molecules. These molecules are studied by theoretical calculations, using Hartree-Fock and Moller-Plesset (MP3 and MP4) theories, to determine the dissociation energies of the molecules. The primary result of the study is that stable molecules can result from oxygen insertion but that oxygen-oxygen proximity destabilizes the insertion products.

Models, Molecular↗
PubMed2005

Why isn't the N20 dodecahedron ideal for three-coordinate nitrogen?

Nitrogen molecules are the focus of much attention for their potential as high-energy density materials. The usefulness of such molecules as energy sources depends on the stability of the molecules with respect to dissociation. Many such molecules dissociate too easily to be a stable fuel, and the reasons for such instability are related to the details of structure and bonding of the molecule. Such details will be examined for isomers of the molecule N20. N20 has a highly symmetric isomer in which the 20 atoms occupy the vertexes of a dodecahedron. This isomer is a cage molecule in which all of the faces are regular pentagons that have interior angles of 108 degrees . These angles are very close to the known bond angles in very stable nitrogen compounds such as ammonia. Such a structure with only pentagons should provide an ideal bonding environment for three-coordinate nitrogen. However, by use of theoretical calculations including density-functional theory and fourth-order perturbation theory, along with the Dunning correlation-consistent basis sets, it will be shown that dodecahedral N20 is not the most stable cage for N20. The reasons why will be discussed in terms of the structure and bonding of the molecules.

Computer Simulation↗
PubMed2003

What makes an N12 cage stable?

Much recent attention has been given to molecules containing only nitrogen atoms. Such molecules N(x) can undergo the reaction N(x) --> (x/2)N(2), which is very exothermic. These molecules are potential candidates for high energy density materials (HEDM). However, many all-nitrogen molecules dissociate too easily to be stable, practical energy sources. It is important to know which nitrogen molecules will be stable and which will not. In the current study, a variety of N(12) cages with all single bonds are examined by theoretical calculations to determine which ones are the most thermodynamically stable. Calculations are carried out using Hartree-Fock (HF) theory, gradient-corrected density functional theory (DFT), and Moller-Plesset perturbation theory (MP2 and MP4). Relative energies among the various isomers are calculated and trends are examined in order to determine which structural features lead to the most energetically favorable molecules.

Energy Transfer↗