With the aim of exploring the electronic and optical properties of some interesting conductive copolymers in view of potential applications, a regular oligomer systems made of aniline and three reference heterocyclic compounds (pyrrole, thiophene and furan) are studied using density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations at B3LYP/6-31+G(d,p) le...

In this study, the complexation of 2,3-dihydro-1H-phenothiazine-4(5aH)-one with 14 various cations were investigated by density functional theory. At the outset, the structures of the ligand, different cations and their derived complexes were optimized geometrically. Then, IR calculations were performed on them in order to acquire the formation enthalpy and Gibbs free energy values. The obtaine...

The response of an extended periodic system to a homogeneous field ~of wave-vector q50) cannot be obtained from a q50 time-dependent density functional theory ~TDDFT! calculation, because the RungeGross theorem does not apply. Time-dependent current–density functional theory is needed and demonstrates that one key ingredient missing from TDDFT is the macroscopic current. In the low-frequency li...

the interaction of magnesium hydrate at the phosphate oxygen atom of the pyrimidine nucleotides (cmp,ump,dtmp) were studied at the hartree-fock level theory. we used lanl2dz basis set for mg and 6-31g* basis set for atoms.the basis set superposition error (bsse) begins to converge for used method/basis set. the gauge-invariant atomic orbital (giao) method and the continuous-set-of-gauge-transfo...

ab initio calculations at the density functional theory (dft) and the second-order møller−plessetperturbation theory levels with 6-31+g(d), 6-31g(d) basis sets for non-metal atoms and lanl2dzfor metal have been performed for the adsorption of dimethyl methylphosphonate (dmmp) on znoby gaussisn 98 program. the calculated rotational constants by b3lyp/6-31g(d) are in moreagreement with the experi...

in this article, the crystallization of polyethylene is investigated by the modified weighted density approximation. also, a direct correlation function of polyethylene based on the rism theory is used. the free energy of a polyethylene is calculated using the density functional theory. the crystallization and also the solid and liquid densities of polyethylene are calculated and compared with ...

Article history: Received 19 April 2008 Received in revised form 2 June 2008 Accepted 15 July 2008 Available online 19 July 2008 PACS: 71.15.-m 71.15.Mb 71.15.Dx

We have studied the medium effects on the frequency-dependent polarizability of water by separating the total polarizability of water clusters into polarizabilities of the individual water molecules. A classical frequency-dependent dipole–dipole interaction model based on classical electrostatics and an Unsöld dispersion formula has been used. It is shown that the model reproduces the polarizab...