ground state geometries have been computed using density functional theory (dft) at b3lyp/6-31g(d,p) level of theory. the excitation energies and spectroscopic parameters have been computed using long range corrected (lc) hybrid functional by time dependent density functional theory (tddft) with lc-blyp level of theory. the polarizable continuum model (pcm) has been used for evaluating bulk sol...

Coupled cluster methods are considered among the most accurate tools in electronic structure theory. Nonetheless relatively limited attempt seems to have been made to extend their applicability to the description of the core-excitation phenomena that are behind largely used spectroscopic techniques like x-ray absorption spectroscopy and x-ray circular dichroism. As a first step to redeem for su...

Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free-energy ensembles in tight-binding, Hartree-Fock, or Kohn-Sham density-functional theory. The canonical density matrix perturbation theory can be used to calculate temperature-dependent response properties from the coupled perturbed self-consistent field equat...

we have performed a density functional theory investigation on the structural and electronic properties of pristine and nitrogen-doped tio2 anatase nanoparticles as the adsorbents for removal and degradation of hydrazine molecules in the environment. we have presented the most stable adsorption configurations and examined the interaction of hydrazine molecule with these doped and undoped nanopa...

importance of covalent bonded two-dimensional monolayer nanostructures and also hydrocarbons is undeniably responsible for creation of new fascinating materials like polyphenylene polymer, a hydrocarbon super honeycomb network, so-called porous graphene. the mechanical properties of porous graphene such as its young’s modulus, poisson’s ratio and the bulk modulus as the determinative properties...

tetrahedrane is most strained and the smallest cage compound. it attracts organic chemists because ofits unusual bonding nature and highly symmetrical structure. however, many efforts to isolate theparent tetrahedrane have been unsuccessful because of the high reactivity and very short lifetimecaused by the strain in this molecule. modeling of molecules for determination of structuralproperties...

in this paper, we used quantum chemical approach to shed light on the catalytic mechanism of γ-carbonic anhydrase (γ-ca) to convert carbon dioxide to bicarbonate ion. density functional theory (dft) using b3lyp and ub3lyp functional and three split-valance including 6-31g*, 6-311g** and 6-311++g** basis sets were used to calculate the details of electronic structure and electronic energy of act...

for analyzing of compositions molecular orbitals in this article in order to combination only- xylometazolin-c7 x2 (xy) and c60– xylometozolin-c65-x2 (fxy), first got energies of highest occupied molecular orbital (homo) and lowest unoccupied molecular orbital (lumo) by using nbo analyze in gaussian 03 software. then, occupancy parameter, gap of energy, and δnmax were calculated   by support of...