International Journal of Molecular Sciences

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Open AccessNew Book Received

Quantum Systems in Chemistry and Physics. Volume 1: Basic Problems and Model Systems,Volume 2: Advanced Problems and Complex Systems, Granada, Spain (1997). Edited by Alfonso Hernández-Laguna

by Shu-Kun Lin

Int. J. Mol. Sci. 2000, 1(3), 61-62; https://doi.org/10.3390/ijms1030061 - 30 Sep 2000

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Abstract

These two volumes [1] are volumes 2 and 3 of the series Progress in Theoretical Chemistry and Physics [2,3].[...] Full article

133 KiB

Open AccessArticle

The Magnetic Shielding Polarizabilities of Some Tetrahedral Molecules

by Martin Grayson and Paul Chittenden

Int. J. Mol. Sci. 2000, 1(3), 49-60; https://doi.org/10.3390/ijms1030049 - 09 Sep 2000

Cited by 3 | Viewed by 7650

Abstract

TMS is the commonest standard reference for both protons and ¹³C NMR spectroscopy. The Magnetic Shielding and its Polarizabilities, plus the static polarizability have been calculated for TMS, tetramethyl ammonium cation and 2,2-dimethylpropane. An investigation of continuum solvation effects on these highly [...] Read more.

TMS is the commonest standard reference for both protons and ¹³C NMR spectroscopy. The Magnetic Shielding and its Polarizabilities, plus the static polarizability have been calculated for TMS, tetramethyl ammonium cation and 2,2-dimethylpropane. An investigation of continuum solvation effects on these highly symmetrical molecules, whose first surviving electric moment is the octopole, showed interaction with solvent makes little change to these magnetic properties. This small change is however consistent with both the high symmetry of the molecules and the available extensive experimental data for TMS. A rationalization of the signs and magnitudes of A in a sequence of related molecules has been suggested. Full article

50 KiB

Open AccessArticle

Density Functional Studies of Molecular Polarizabilities. 10. Fulvenes and Fulvalenes

by Alan Hinchliffe and Humberto J. Soscún Machado

Int. J. Mol. Sci. 2000, 1(3), 39-48; https://doi.org/10.3390/ijms1030039 - 04 Sep 2000

Cited by 19 | Viewed by 9789

Abstract

We report accurate Ab Initio Hartree Fock (HF) and Density Functional Theory (DFT) studies of the static dipole polarizabilities and first hyperpolarizabilities of the [n] fulvene and the [n,m] fulvalene series of molecules (with n, m = 3,5,7). Calculations are also reported for [...] Read more.

We report accurate Ab Initio Hartree Fock (HF) and Density Functional Theory (DFT) studies of the static dipole polarizabilities and first hyperpolarizabilities of the [n] fulvene and the [n,m] fulvalene series of molecules (with n, m = 3,5,7). Calculations are also reported for the parent cycloalkenes: cyclopropene, cyclopentadiene and cycloheptatriene (1-3 respectively). Geometries were optimized at the HF/6-311G(3d,2p) level of theory. All the fulvenes (4-6) and the smaller fulvalenes (7, 9 and 10) are found to be planar. Pentaheptafulvalene (11) is slightly non-planar whilst heptafulvalene (12) has a folded C_2h structure. Calculated C-C bond lengths are consistently smaller than the experimental values. Dipole polarizabilities and non-zero hyperpolarizabilities were calculated at the HF/6-311++G(3d,2p) and BLYP/6-311++G(3d,2p) levels of theory, using HF/6-311G(3d,2p) geometries. Dipole polarizabilities correlate well with those given on the basis of atom additivity. Molecules (8), (9) and (11) show very large dipole hyperpolarizabilities. Full article

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370 KiB

Open AccessArticle

Magnitude of the First and Second Neighbour Magnetic Interactions in the Spin Chain Compound Li₂CuO₂

by C. De Graaf, I. De P. R. Moreira and F. Illas

Int. J. Mol. Sci. 2000, 1(3), 28-38; https://doi.org/10.3390/ijms1030028 - 23 Aug 2000

Cited by 6 | Viewed by 8680

Abstract

State-of-the-art molecular quantum chemical techniques have been applied to the solid-state compound Li₂CuO₂ in order to derive accurate estimates of the in-chain magnetic interactions. In the present work, the magnitude of the nearest neighbour and next nearest neighbour magnetic coupling [...] Read more.

State-of-the-art molecular quantum chemical techniques have been applied to the solid-state compound Li₂CuO₂ in order to derive accurate estimates of the in-chain magnetic interactions. In the present work, the magnitude of the nearest neighbour and next nearest neighbour magnetic coupling constants is investigated from first principles embedded cluster calculations. The convergence of the results is carefully tested for the cluster size. In contrast to the earlier findings, it is predicted that J₂ is only ~15% of J1. In particular, it is shown that a large J₂ appears when the Li⁺ ions are not explicitly included in the calculation. Full article

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Int. J. Mol. Sci., Volume 1, Issue 3 (September 2000) – 4 articles , Pages 28-62

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