Simple basis sets for molecular wavefunctions containing atoms from Z = 2 to Z = 54

1974 ◽  
Vol 60 (12) ◽  
pp. 4725-4729 ◽  
Author(s):  
Carla Roetti ◽  
Enrico Clementi
Keyword(s):  
Basis Sets ◽  
Simple Basis ◽  
Molecular Wavefunctions

An Xα ab initio Calculation of the Charge and Spin-Density in Cs3Mo(NCS)6 Crystals Compared With Experiment

1990 ◽  
Vol 43 (6) ◽  
pp. 1097 ◽  
Author(s):  
BN Figgis ◽  
PA Reynolds
Keyword(s):  
Charge Transfer ◽  
Electric Field ◽  
Ab Initio ◽  
External Electric Field ◽  
Ab Initio Calculation ◽  
Spin Transfer ◽  
Basis Sets ◽  
Simple Basis ◽  
Metal Ligand ◽  
Complex Ion

We have performed ab initio discrete variational Xα calculations on a Cs18[Mo(NCS)6]15+ cluster, with the external electric field appropriate for a Cs3Mo(NCS)6 crystal. The calculations show both σ and π bonding, and also the participation of diffuse molybdenum- centred orbitals . Compared with the charge density experiment these effects are qualitatively correct but are underestimated. We performed further calculations successively removing the external electric field and the 18 Cs+ neighbours . The effects on the calculated metal- ligand bonding in the complex ion are negligible. This is not in agreement with experiment, so that these calculations which invoke only electrostatic effects and orthogonality with neighbouring ions and which also use only simple basis sets are not adequate. Further calculations on the Cr(NCS)63- and W(NCS)63- ions show increasing covalence from chromium to tungsten as expected. The spin transfer to the ligand is calculated to triple, but charge transfer is almost constant.

Die Verwendung reiner Gauß-Basis-Funktionen zur Beschreibung der Elektronenbeugung an Gasmolekülen unter Berücksichtigung der chemischen Bindung / The Use of Gauss-Lobe-Functions for Calculating the Electron Diffraction Intensity from Gas Molecules under Consideration of Chemical Bond

1974 ◽  
Vol 29 (7) ◽  
pp. 1023-1033 ◽  
Author(s):  
Armin Haberl ◽  
Joachim Haase
Keyword(s):  
Electron Diffraction ◽  
Chemical Bond ◽  
Electron Scattering ◽  
Basis Sets ◽  
Molecular Vibration ◽  
Inelastic Electron ◽  
Diffraction Intensity ◽  
Analytic Expressions ◽  
Gas Molecules ◽  
Molecular Wavefunctions

The first Born Expression of elastic and inelastic electron scattering from gas molecules of any svmmetry leads to simple analytic expressions if molecular wavefunctions expanded in Gauss-Lobefunctions (GL's) are used and if the effect of molecular vibration is neglected. The result is given and in the case of H2O theoretical intensities are calculated from two HF-wavefunctions with medium sized GL-basis sets [ (5s, 3p/3s,-) and (5s, 4p/5s,-)] and compared with Konaka's experiment.

Electronegativity Equalization and the Deformation of Atomic Orbitals in Molecular Wavefunctions

1988 ◽  
Vol 41 (6) ◽  
pp. 827 ◽  
Author(s):  
E Magnusson
Keyword(s):  
Hydrogen Atom ◽  
Bond Distance ◽  
Basis Sets ◽  
Radial Dependence ◽  
Electronic Charge ◽  
Atomic Orbitals ◽  
Electronegativity Equalization ◽  
Electronegativity Difference ◽  
The Mean ◽  
Molecular Wavefunctions

Electronegativity equalization, which must accompany the formation of a chemical bond, occurs when electronic charge is transferred between the bound atoms but also by changes in the radial dependence of the atomic orbitals involved in the bonding. The degree of contraction or expansion of the atomic orbitals may be studied by analysing ab initio MO wavefunctions calculated with flexible basis sets. The effects on the hydrogen orbital are marked, the 1sHmean radius being progressively reduced by 9-23% across the series of first row hydrides (BH3 to HF) from its value in the hydrogen atom. The mean radius of the carbon 2p function in the wavefunctions of substituted methanes (CH3BH2 to CH3F) is correspondingly reduced by 2-19% from its free-atom value. Orbital contraction (or expansion) is dependent on bond distance, on the electronegativity difference of the bound atoms, and, because it varies from one MO to another, on the nature of the MO'S. The effects are greatest in MO'S which are strongly bonding.

Constrained density matrix study of simple basis sets for helium

1973 ◽  
Vol 58 (6) ◽  
pp. 2388-2392 ◽  
Author(s):  
George A. Henderson ◽  
Michael A. Lee
Keyword(s):  
Density Matrix ◽  
Basis Sets ◽  
Simple Basis
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