The absolutely localized molecular orbital (ALMO) model is a fully variational approach which permits polarization of molecules interacting in a cluster while prohibiting charge-transfer (or dative interactions) between individual molecules. The ALMO model can be applied within any density functional theory calculation--the B3LYP functional is employed in this work. ALMO DFT calculations of obs...

Phenylalanine (Phe) is one of the amino acids that cannot be produced in body and must ingested through diet. Tyrosine (Tyr) also a non-essential acid can by Phe hydroxylation liver when dietary intake Tyr low. Structure analysis very important to know correct synthesis reactivity molecule. In this study, characterization molecules were investigated using quantum chemical calculations. The mole...

Planar tetracoordinate nitrogen (ptN) has been successfully extended as a new branch of planar chemistry. As the simplest type of ptN, penta-atomic species (pptN, e.g., NAl(4)(-)) are known to have a "delocalized" molecular environment with a single bond between the central N and the ligand. In this paper, through an extensive isomeric search of a series of group V-based systems NXAl(3)(+) (X =...

We investigate the performance of CC2 and TDDFT/CAM-B3LYP for the calculation of two-photon absorption (TPA) strengths and cross sections and contrast our results to a recent coupled cluster equation-of-motion (EOM-EE-CCSD) benchmark study [K. D. Nanda and A. I. Krylov, J. Chem. Phys., 2015, 142, 064118]. In particular, we investigate whether CC2 TPA strengths are significantly overestimated co...

We report the results of theoretical calculations on the optimized structures and relative energies between the D4d and D2 symmetry structures for double-decker type phthalocyanine compounds, Ti(Pc)2, Ti(Pc)2(+), Sn(Pc)2, Sn(Pc)2(+), Sc(Pc)2 and Sc(Pc)2(+), using eighteen types of functionals: B3LYP, B3PW91, B3P86, PBE1PBE, BHandHLYP, BPW91, BP86, M06, M06-2x, M06-HF, M06L, LC-BPW91, LC-ωPBE, C...

B3LYP/6-31G* calculations have been performed, to compute the kinetic isotope effects (KIEs) on the rate of ring opening of cyclopropylcarbinyl radical (1) to 3-buten-1-yl radical (2) at 20 K by tunneling. The most striking result of our small curvature tunneling calculations is the prediction of a 2.7-fold increase in the rate of reaction by substitution of D(2) for H(2) at C(1). The origin of...

Large-scale density functional theory calculations (DFT) found various types of binding of an unsaturated hydrocarbon (C2H2 and C2H4) to a ZSM-5 zeolite extraframework copper cation. We employed the DFT calculations based on the B3LYP functional to obtain local minima of an unsaturated hydrocarbon adsorbed on one or two copper cations embedded inside ZSM-5, and then compared their stabilization...

Results of detailed calculations for SrTiOs (100) surface relaxation and the electronic structure for the two different terminations (SrO and TiO2) are discussed. These are based on ab initio Hartree-Fock (HF) method with electron correlation corrections and Density Functional Theory (DFT) with different exchange-correlation functionals, including hybrid (B3PW, B3LYP) exchange techniques. Resul...

The acidity constants of the compounds, including five-membered heterocyclic (pyrrole, thiophene, furan or thiazole) ring systems were determined at 25oC in aqueous solitions, applying UV-Vis spectroscopic method that uses absorbance diagrams,. In order to explain the pKa values obtained, also the molecule conformations of the bases and their corresponding conjugate acids were investigated, app...

The isotropic and anisotropic Raman spectra of acetone and deuterated acetone isolated in an argon matrix have been recorded for the understanding of noncoincidence effect (NCE) phenomenon. According to the matrix isolated Raman spectra and DFT calculations, we proposed aggregated model for the explanations of the acetone C=O vibration NCE phenomenon and its concentration effect. The experiment...