Normal Vibrational Mode Analysis and Assignment of Benzimidazole by ab Initio and
Density Functional Calculations and Polarized Infrared and Raman Spectroscopy
M. A. Morsy
M. A. Al-Khaldi
A. Suwaiyan
10.1021/jp0256948.s002
https://acs.figshare.com/articles/journal_contribution/Normal_Vibrational_Mode_Analysis_and_Assignment_of_Benzimidazole_by_ab_Initio_and_Density_Functional_Calculations_and_Polarized_Infrared_and_Raman_Spectroscopy/3724128
Molecular structure and fundamental vibrational frequencies of benzimidazole (BZI) are reported using ab
initio-Hartree−Fock (HF) and density functional theory (DFT) methods at different levels of calculation.
Observed polarized IR and Raman fundamentals of polycrystalline, single crystal, KBr−BZI disks, and gaslike
samples are analyzed and assigned by comparison to the computed values. The assignment of fundamentals
shows a one-to-one correspondence between the observed and calculated fundamentals using the BLYP/6-31G* level of calculation without applying any scaling factor except for XH stretching (X represents C or
N), where a 0.995 scaling factor has been used. Hydrogen bonding and its effects on some normal vibrational
modes are discussed. The results show that the nonscaled BLYP/6-31G* level of calculation may be used as
a reference for assessing the intermolecular hydrogen bonding effect.
2002-09-05 00:00:00
calculation
gaslike samples
factor
HF
Normal Vibrational Mode Analysis
BZI
BLYP
Raman Spectroscopy Molecular structure
DFT
IR
XH
Density Functional Calculations
results show
vibrational modes
vibrational frequencies
Raman fundamentals
ab Initio