Anharmonic vibrational analysis of uracil by ab initio Hartree–Fock and density functional theory calculations

2009 ◽  
Vol 895 (1-3) ◽  
pp. 18-20 ◽  
Author(s):  
Tabish Rasheed ◽  
Shabbir Ahmad ◽  
S.M. Afzal ◽  
K. Rahimullah
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Hartree Fock

Conformational and Vibrational Analysis of 2,4-, 2,5- and 2,6-Difluorobenzaldehydes by ab initio Hartree-Fock and Density Functional Theory Calculations

2008 ◽  
Vol 63 (3-4) ◽  
pp. 175-182 ◽  
Author(s):  
Adnan Sağlam ◽  
Fatih Ucun
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Molecular Structures ◽  
Basis Set ◽  
Functional Theory ◽  
Vibrational Assignments ◽  
Hartree Fock ◽  
The Mean

The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments of the two planar O-cis and O-trans rotomers of 2,4-, 2,5- and 2,6-difluorobenzaldehyde have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with the 6-311++G(d,p) basis set level. The calculations were adapted to the CS symmetries of all the molecules. The O-trans rotomers with lower energy of all the compounds have been found as preferential rotomers in the ground state. The mean vibrational deviations between the vibrational frequency values of the two conformers of all the compounds have been shown to increase while the relative energies increase, and so it has been concluded that the higher the relative energy between the two conformers the bigger is the mean vibrational deviation.

Sign in / Sign up

Export Citation Format

Share Document