研究者詳細 - 河村　光晶

We develop Kω, an open-source linear algebra library for the shifted Krylov subspace methods. The methods solve a set of shifted linear equations (zkI−H)x(k)=b(k=0,1,2,…) for a given matrix H and a vector b, simultaneously. The leading order of the operational cost is the same as that for a single equation. The shift invariance of the Krylov subspace is the mathematical foundation of the shifted Krylov subspace methods. Applications in materials science are presented to demonstrate the advantages of the algorithm over the standard Krylov subspace methods such as the Lanczos method. We introduce benchmark calculations of (i) an excited (optical) spectrum and (ii) intermediate eigenvalues by the contour integral on the complex plane. In combination with the quantum lattice solver HΦ, Kω can realize parallel computation of excitation spectra and intermediate eigenvalues for various quantum lattice models.

Effect of spin fluctuations on superconductivity in V and Nb: A first-principles study

Tsutsumi, K; Hizume, Y; Kawamura, M; Akashi, R; Tsuneyuki, S

PHYSICAL REVIEW B 102 ( 21 ) 2020年12月 [査読有り]

DOI Web of Science

記述言語：英語掲載種別：研究論文（学術雑誌）共著

RESPACK: An ab initio tool for derivation of effective low-energy model of material

中村和磨, Yoshimoto Yoshihide, Nomura Yusuke, Tadano Terumasa, Kawamura Mitsuaki, Kosugi Taichi, … 全著者表示

Computer Physics Communications 261 107781-1 - 107781-20 2020年12月 [査読有り]

DOI Web of Science CiNii Research

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier 共著

RESPACK is a first-principles calculation software for evaluating the interaction parameters of materials and is able to calculate maximally localized Wannier functions, response functions based on the random phase approximation and related optical properties, and frequency-dependent electronic interaction parameters. RESPACK receives its input data from a band-calculation code using norm-conserving pseudopotentials with plane-wave basis sets. Automatic generation scripts that convert the band-structure results to the RESPACK inputs are prepared for xTAPP and Quantum ESPRESSO. An input file for specifying the RESPACK calculation conditions is designed pursuing simplicity and is given in the Fortran namelist format. RESPACK supports hybrid parallelization using OpenMP and MPI and can treat large systems including a few hundred atoms in the calculation cell.

Vapochromism induced by intermolecular electron transfer coupled with hydrogen-bond formation in zinc dithiolene complex

Yokomori, S; Dekura, S; Fujino, T; Kawamura, M; Ozaki, T; Mori, H

JOURNAL OF MATERIALS CHEMISTRY C 8 ( 42 ) 14939 - 14947 2020年11月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

Anisotropic Triangular Lattice Realized in Rhenium Oxychlorides A₃ReO₅Cl₂ (A = Ba, Sr)

Hirai, D; Yajima, T; Nawa, K; Kawamura, M; Hiroi, Z

INORGANIC CHEMISTRY 59 ( 14 ) 10025 - 10033 2020年7月 [査読有り]

DOI Web of Science PubMed

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Possible Kitaev Quantum Spin Liquid State in 2D Materials with S=3/2

Xu, CS; Feng, JS; Kawamura, M; Yamaji, Y; Nahas, Y; Prokhorenko, S; Qi, Y; Xiang, HJ; Bellaiche, L