Ab-initio molecular calculations

Recently, we have developed a full theoretical treatment of electron capture processes involving an ab initio molecular calculation of the potential energy curves and of the radial and rotational couplings followed, according to the collision energy range concerned, by a semi-classical [21-23] orquantal [24] collision treatment. 

Tad)eddine, M. and Flament, J.P. (1999) Analysis of a nonlinear optical response of CN- ions adsorbed on metal electrode tentative interpretation by means of ab initio molecular calculations. Chemical Physics, 240, 39-50. 

In the following, we first describe (Section 13.3.1) a statistical mechanical formulation of Mayer and co-workers that anticipated certain features of thermodynamic geometry. We then outline (Section 13.3.2) the standard quantum statistical thermodynamic treatment of chemical equilibrium in the Gibbs canonical ensemble in order to trace the statistical origins of metric geometry in Boltzmann s probabilistic assumptions. In the concluding two sections, we illustrate how modem ab initio molecular calculations can be enlisted to predict thermodynamic properties of chemical reaction (Sections 13.3.3) and cluster equilibrium mixtures (Section 13.3.4), thereby relating chemical and phase thermodynamics to a modem ab initio electronic stmcture picture of molecular and supramolecular interactions. 

They applied the same pseudopotential as before in the paper with title ab initio molecular calculations with pseudopotentials calculations of double-zeta quality on ethylene, acetylene, and water , but a linear combination of FSGO has been used in the following articles. A description of C-C bond for double and triple bond has been given in the pseudopotential-FSGO method. 

Proton NMR studies of N-methyl formamide (NMF) and NMA at high dilution in deuterated solvents have shown that the level of cis isomer of NMF is 8% in water, 10.3% in chloroform, 8.8% in benzene, and 9.2% in cyclohexane, while the level of cis-NMA (a model for the secondary peptide bond) is 1.5% in water and does not change very much in nonpolar solvents [18]. Ab initio molecular calculations suggest that the small difference in dipole moments in cis and trans forms explain the relative insensitivity of amides to solvent change, unlike esters [22,41], This may be explained by nearly identical free energies of solvation for the two isomers [18]. The energy difference between cis and trans isomers in aqueous solution (AG° = 2.5 kcal mol-1) accounts for the preferential trans conformation adopted by most peptide bonds. Similar results were obtained with nonproline tertiary amides [22]. 

As benchmark systems for the test of advanced ab initio molecular calculations (in particular, QED contributions)... 

C. Teichteil, M. PelUsier, F. Spiegelmann. Ab Initio Molecular Calculations Including Spin-Orbit Coupling. 1. Method and Atomic Tests. Chem. Phys., 81 (1983) 273-282. 

Many types of basis set have been examined and two of these have come to dominate the area of ab initio molecular calculations. These two, which we refer to as the gaussian and the Slater-type-orbital (STO) basis sets, are actually very similar in many important respects. 

Abstract Rate constants for charge transfer processes in the interstellar medium are calculated using ab-initio molecular calculations. Two important reactions are presented the recombination of Si + and Si + ions with atomic hydrogen and helium which is critical in determining the fractional abundances of silicon ions, and the C+ + S -> C + S+ reaction, fundamental in both carbon and sulphur chemistry. 

Teichteil C, Pelissier M, Spiegeknann F. Ab initio molecular calculations including spin-orbit coupling. I. Method and atomic tests. Chem Phys. 1983 81 273-282. 

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