Prediction of longitudinal electric polarizabilities of conjugated chain molecules by scaling of abinitio calculations

1985 ◽  
Vol 63 (7) ◽  
pp. 1631-1634 ◽  
Author(s):  
V. P. Bodart ◽  
J. Delhalle ◽  
J. M. André ◽  
J. Zyss
Keyword(s):  
Basis Sets ◽  
Minimal Basis ◽  
Chain Molecules ◽  
Electric Polarizabilities ◽  
Abinitio Calculations

The predictive use of scaled minimal basis sets calculations of electric polarizabilities for large hydrocarbons, proposed by Chablo and Hinchliffe, is further assessed by considering two series of oligomers, H—(CH=CH)n—H and H—(C≡C)n—H where n = 1, 2, 3, and 4. It is then applied to the yet experimentally untested vinylacetylene, 1,5-hexadiene-3-yne, and 1,5,9-decatriene-3,7-diyne for their polarizability.

scholarly journals Quasi-Atomic Bond Analyses in the Sixth Period: I. Relativistic Accurate Atomic Minimal Basis Sets for the Elements Cesium to Radon

2019 ◽  
Vol 123 (25) ◽  
pp. 5242-5248 ◽  
Author(s):  
George Schoendorff ◽  
Aaron C. West ◽  
Michael W. Schmidt ◽  
Klaus Ruedenberg ◽  
Mark S. Gordon
Keyword(s):  
Basis Sets ◽  
Minimal Basis

Molecule intrinsic minimal basis sets. II. Bonding analyses for Si4H6 and Si2 to Si10

2004 ◽  
Vol 120 (6) ◽  
pp. 2638-2651 ◽  
Author(s):  
W. C. Lu ◽  
C. Z. Wang ◽  
M. W. Schmidt ◽  
L. Bytautas ◽  
K. M. Ho ◽  
...  
Keyword(s):  
Basis Sets ◽  
Minimal Basis

The simplified ab initio method calculation of linear polarizability

1973 ◽  
Vol 26 (5) ◽  
pp. 921 ◽  
Author(s):  
RD Brown ◽  
GR Williams
Keyword(s):  
Ab Initio ◽  
Small Molecules ◽  
Basis Set ◽  
Basis Sets ◽  
Orbital Method ◽  
Polarizability Anisotropy ◽  
Minimal Basis ◽  
Hartree Fock ◽  
Numerical Performance ◽  
Experimental Values

The simplified ab-initio molecular-orbital method described previously is particularly suited to the calculation of polarizabilities by the non-perturbative coupled Hartree-Fock technique. Trial calculations on CO and HF, for which comparison with corresponding ab-initio calculations is possible, show that the method gives an adequate numerical performance. Minimal basis set calculations in general tend to give values that are considerably too low because of inadequate flexibility of the basis and this is the origin of the large discrepancy between theory and experiment, especially for small molecules. ��� Results are also reported for N2O and O3. For these larger systems the SAI results with minimal basis sets are noticeably nearer experimental values. The polarizability anisotropy for N2O is particularly well reproduced by the SAI method. �

The Rotational Barrier About the Disulphide Bridge in Dimethyl Disulphide: An Ab Initio Study

1984 ◽  
Vol 39 (5) ◽  
pp. 495-498
Author(s):  
V. Renugopalakrishnan ◽  
R. Walter
Keyword(s):  
Ab Initio ◽  
Rotational Barrier ◽  
Basis Set ◽  
Basis Sets ◽  
Disulphide Bridge ◽  
Minimal Basis ◽  
Gaussian Basis Sets ◽  
Type Function ◽  
Dimethyl Disulphide ◽  
Extended Basis

An ab initio molecular orbital technique was used to investigate the rotational barrier about the disulphide bridge in dimethyl disulphide. Various minimal and extended basis sets were used in the calculations. The chosen minimal basis set was the STO-3G set, and the extended basis sets were the STO 4-31G set, the Dunning and Hay set consisting of contracted Gaussian basis sets: [2s], [3s, 2p] and [6s, 4p] for H, C, and S atoms, and the Dunning and Hay basis set augmented with a d-type function on S atoms. The total energy was calculated as a function of the torsion angle about the disulphide bond. The barrier to rotation about this bond was found to be two-fold in nature, in accordance with previous findings. The heights of the barriers were observed to depend upon the basis set and input geometry. For our particular choice of basis sets and input geometry, the calculated value of the eis and trans barriers ranged from 12.68 to 16.49 kcal/mol and from 6.23 to 8 kcal/mol, respectively. Inclusion of a d-type function in the basis sets was found to result in better agreement between the calculated and experimental values, thereby emphasizing the need for considering 3d orbitals of sulphur in MO calculations

scholarly journals Infrared Spectrum for the New Exobiological Nanomolecules Asi, Csi, Tsi and Gsi

2021 ◽  
pp. 25-31
Author(s):  
Ricardo Gobato ◽  
Alireza Heidari ◽  
Lauro Figueroa Valverde ◽  
Abhijit Mitra
Keyword(s):  
Infrared Spectrum ◽  
Quantum Chemistry ◽  
Ab Initio ◽  
Basis Sets ◽  
Minimal Basis ◽  
Hartree Fock ◽  
Standard Bases ◽  
Quantum Chemistry Calculations ◽  
Computational Calculations ◽  
Correlation Consistent

The core of the work is based on the replacement of carbon atoms by silicon atoms, on the basis of four standard bases of DNA: A, C, G and T (adenine, cytosine, guanine, thymine). Determining with minimum computational methods via ab initio Hartree-Fock methods, infrared spectrum and their peak absorbance frequencies. The option for simple replacement of carbon by silicon is due to the peculiar characteristics between both. Atomic interactions under non-carbon conditions were studied, with only the Hydrogen, Silicon, Nitrogen and Oxygen atoms, in CNTP, for the four standard bases of DNA, A, C, G and T, thus obtaining by quantum chemistry four new compounds, named here as: ASi, CSi, GSi and TSi. Computational calculations admit the possibility of the formation of such molecules, their existence being possible via quantum chemistry. Calculations obtained in the ab initio Unrestricted and Restrict Hartree-Fock method, (UHF and RHF) in the set of basis used Effective core potential (ECP) minimal basis, UHF CEP-31G (ECP split valance) and UHF CEP-121G (ECP triple-split basis), CC-pVTZ (Correlation-consistent valence-only basis sets triple-zeta) and 6-311G**(3df, 3pd) (Gaussian functions quadruple-zeta basis sets).

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