Entity

Time filter

Source Type


Nakata H.,Tokyo Institute of Technology | Nakata H.,Research Cluster for Innovation | Fedorov D.G.,Japan National Institute of Advanced Industrial Science and Technology | Yokojima S.,Research Cluster for Innovation | And 3 more authors.
Theoretical Chemistry Accounts | Year: 2014

The analytic energy gradient for the point charge approximation of the embedding potential is derived in the framework of unrestricted Hartree-Fock based on the fragment molecular orbital method (FMO). For this goal, we derive the necessary coupled-perturbed unrestricted Hartree-Fock equations, describing the response terms arising from the use of embedding atomic charges in dimer calculations. By a comparison to numerical gradients and with the aid of molecular dynamics, we show that the gradients have a high accuracy. A speed-up of the factor 7.3 is obtained for the largest system, when approximated potentials are used relative to the exact two-electron embedding. We apply the FMO method to polymer radicals and show that it has satisfactory accuracy in reproducing the geometries and energies of polymer radical reactions. © Springer-Verlag Berlin Heidelberg 2014. Source


Nakata H.,Tokyo Institute of Technology | Nakata H.,Research Cluster for Innovation | Nakata H.,Japan Society for the Promotion of Science | Fedorov D.G.,Japan National Institute of Advanced Industrial Science and Technology | And 4 more authors.
Journal of Chemical Theory and Computation | Year: 2014

We developed an approach to calculate normal Raman activities based on the fragment molecular orbital method. For this purpose, we derived the FMO gradient and coupled-perturbed Hartree-Fock equations in the presence of the static electric field. The accuracy is evaluated in comparison with full ab initio calculations for a set of closed-shell and radical systems. We applied the method to calculate Raman and IR spectra of a polystyrene oligomer and crambin (PDB: 1CRN) and performed an assignment of peaks based on localized normal modes. The computational timings demonstrate the efficiency of the method. © 2014 American Chemical Society. Source

Discover hidden collaborations