We analyze the feasibility of extremely rapid estimation of correlation energy from the HF-SCF charge distribution in w Ž . x closed-shell molecules. In Kristyan’s previous work Chem. Phys. 224 1997 33-51 a simple linear relationship using atomic correlations was developed in order to calculate correlation energy of molecules. This method has been further refined in this Letter. The proposed me...

The Infrared spectrum of L-phenylalanine L-phenylalaninium-benzoic acid (LPB) was recorded and analyzed in the region 4000–400 cm. Optimized geometrical structures and harmonic vibrational frequencies have been computed by the B3 based (B3LYP) density functional method using 6-31+G (d, p). The calculated first hyperpolarizability is comparable with the reported value of similar structures and m...

To further extend the EEM approach to improve its accuracy, a new approach, in which the different connectivities and hybridized states are introduced to represent the different chemical environments, has been developed. The C, O and N atoms are distinguished between different hybridized states. Different states of hydrogen atoms are defined according to their different connectivities. Furtherm...

The B3LYP density function was used with the 6-31G(d) basis set to perform relaxed energetic contour maps of the charged form of j-carrabiose in the gas phase and for the neutral form first in the gas phase and then by simulating the presence of water as solvent using the Onsager model. Only one starting conformation has been considered to perform all the calculations. Rigid energetic maps have...

A variety of novel 5-aryl thiophenes 4a-g containing sulphonylacetamide (sulfacetamide) groups were synthesized in appreciable yields via Pd[0] Suzuki cross coupling reactions. The structures of these newly synthesized compounds were determined using spectral data and elemental analysis. Density functional theory (DFT) studies were performed using the B3LYP/6-31G (d, p) basis set to gain insigh...

In the present study, theoretical chemical reactivates Photo isomerization in Cis-Retinal as a Natural Photo switch in Vision. DFT hybrid functional, B3LYP and, post-HF method, were the theoretical methods applied utilizing G09 software. 6-31G+ (d,p) basis set employed for structural optimizations, and single point computations performed using B3LYP/6-31G+(d,p). The isomers cis molecule retinal...

Basicity constants for a series of 3,7-diazabicyclo[3.3.1]nonane derivatives in acetonitrile with a variation over 13 orders of magnitude have been determined using a spectrophotometric titration technique. An excellent correlation between basicity and calculated proton affinities obtained at PCM-B3LYP/6-31+G(d)//B3LYP/6-31G(d) level was found. The results are discussed in terms of substituent ...

A series of monocyclic planar inorganic compounds have been optimized at the B3LYP/6-311+G* level. GIAO-B3LYP nucleus-independent chemical shifts (NICS) profiles calculated in the perpendicular direction of each ring show that the series of analyzed compounds can be classified in three groups according to their aromatic, non-aromatic or antiaromatic character. Our results suggest exercising cau...

FT-IR and FT-Raman spectra of 2-phenyl-4H-3,1-benzoxazin-4-one were recorded and analyzed. The vibrational wavenumbers of the title compound have been computed using the HartreeFock and B3LYP levels of theory using 6-31G* basis set and compared with the experimental data. The results indicate that B3LYP calculations approximate the observed fundamental wavenumbers much better than the HF result...

The electronic and geometric structures of endo,endo-tetracyclo[4.2.1.1.0] dodeca-4,9-diene(TTDD) molecule have been investigated by ab initio and DFT/B3LYP methods with the 6-31G* and 6-311G* basis sets. The double bonds of TTDD molecule have been endo-pyramidalized. The structure of π-orbitals and their mutual interactions for TTDD molecule have been investigated. The cationic intermediates a...