Journal ArticleDOI
Molvib - A flexible program for force field calculations
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TLDR
MOLVIB as discussed by the authors is a Fortran program for classical harmonic force field calculations on free and crystalline molecules, which is well suited for large overlay calculations and can handle different types of force fields.About:
This article is published in Journal of Molecular Structure.The article was published on 1990-03-01. It has received 654 citations till now. The article focuses on the topics: Cartesian coordinate system & Force field (chemistry).read more
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FT-IR, FT-Raman and DFT quantum chemical study on the molecular conformation, vibrational and electronic transitions of 1-(m-(trifluoromethyl)phenyl)piperazine
TL;DR: The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule and the observed and the calculated frequencies are found to be in good agreement.
Journal ArticleDOI
Analysis of vibrational spectra of 5-fluoro, 5-chloro and 5-bromo-cytosines based on density functional theory calculations
V. Krishnakumar,V. Balachandran +1 more
TL;DR: The geometry, frequency and intensity of the vibrational bands 5-fluoro, 5-chloro and 5-bromo-cytosines were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Yang-Parr (B3LYP) functional and 6-31G* basis set.
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Molecular and vibrational structure of 2-mercapto pyrimidine and 2,4-diamino-6-hydroxy-5-nitroso pyrimidine: FT-IR, FT-Raman and quantum chemical calculations.
V. Krishnakumar,R. John Xavier +1 more
TL;DR: The scaled quantum mechanical (SQM) approach applying selective scaling of the DFT force fields was shown to be superior to the scaling method in its ability to ensure correct band assignments and successful simulation of IR and Raman spectra including band polarisations and intensity patterns.
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An experimental and theoretical study of L-Tryptophan in an aqueous solution, combining two-layered ONIOM and SCRF calculations
Patricio Leyton,Juan E. Brunet,Viviana Silva,Carolina Paipa,María V. Castillo,Silvia Antonia Brandán +5 more
TL;DR: Optimized geometries and relative stabilities for the L-tryptophan zwitterion were calculated while taking into account solvent effects using the self-consistent reaction field (SCRF) theory and significant effects on the geometrical and vibrational frequencies were found for the studied zwittersion.
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Scaled quantum chemical calculations and FT-IR, FT-Raman spectral analysis of 2-methyl piperazine.
V. Krishnakumar,S. Seshadri +1 more
TL;DR: The vibrational spectra of 2-methyl piperazine (2MPZ) have been computed using B3LYP methodology and 6-31G* and 6 -31G** basis sets and were found to be well comparable.
References
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Vibrational analysis of the n-paraffins—II
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Normal Coordinates: General Theory, Redundant Coordinates, and General Analysis Using Electronic Computers
TL;DR: A system of doing normal coordinate analysis is described which is better suited for use with electronic computers than are current methods and the advantage of using linear potential constants in strained and constrained systems is retained.
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Ab initio calculation of the force field of ethylene
Peter Pulay,Wilfried Meyer +1 more
TL;DR: In this paper, the force field of ethylene has been determined by the force method from SCF-MO wavefunctions using a 73 3 + 1 Gaussian lobe basis set.
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A new damped least-squares method for the calculation of molecular force fields
TL;DR: In this article, a modified Gauss method for the calculation of molecular force fields from spectroscopic data is presented, which is capable of overcoming many of the frequently occurring convergence problems in least-squares force field optimization.
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Calculation of inertia defect: Part IV. Ethylene-type molecules
TL;DR: In this paper, the Coriolis coupling constants and the contributions to the inertia defect from individual vibrational modes are evaluated by using the force constants and fundamental frequencies taken from the literature.