月別: 2022年3月

[Published online Journal of Computer Chemistry, Japan Vol.20, 129-131, by J-STAGE]
<Title:> 量子化学計算によるフェニルイソシアネート275 nm第一吸収帯の帰属
<Author(s):> 長沼　優人, 石橋　太祐, 奥山　克彦
<Corresponding author E-Mill:> okuyama.katsuhiko(at)nihon-u.ac.jp
<Abstract:> Abstract: Electronic spectra for the first 275-nm absorption system of phenyl isocyanate observed in a room temperature and in a jet were assigned with an assistance of quantum-chemistry calculation. All vibronic bands in a jet were diffuse with a width of 18 cm^-1, indicating the lower limit of the life time was 204 fs. A suitable pair of a theoretical method and a basis set was selected among combinations of B3LYP, CAM-B3LYP, and MP2 and 18 kinds of basis sets on the basis of molecular-orbital energies and the rotational constant spectroscopically observed. B3LYP/cc-pVTZ and B3YP/aug-cc-pVDZ gave us good results. Time-dependent calculation was performed by two pairs. It was found out that the 275-nm absorption system was assigned as the first ππ* and third excited state and that twonπ* states with a very small oscillator strength were lying in the infrared and visible region. The fast relaxation process observed in a jet was due to an internal conversion to two nπ* states.
<Keywords:> Phenyl isocyanate, Quantum-chemistry calculation, Supersonic-jet spectroscopy, Symmetry assignyment, Absorption system
<URL:> https://www.jstage.jst.go.jp/article/jccj/20/4/20_2021-0051/_article/-char/ja/

[Published online Journal of Computer Chemistry, Japan Vol.20, 132-136, by J-STAGE]
<Title:> FMOプログラムABINIT-MPの整備状況2021
<Author(s):> 望月　祐志, 中野　達也, 佐藤　伸哉, 坂倉　耕太, 渡邊　啓正, 奥脇　弘次, 大島　聡史, 片桐　孝洋
<Corresponding author E-Mill:> fullmoon(at)rikkyo.ac.jp
<Abstract:> We have been developing the ABINIT-MP program for fragment molecular orbital (FMO) calculations over 20 years. In 2021, the Open Version 2 series has started for large scale systems consisting of more than ten thousand fragments. This letter describes the current status of ABINIT-MP, including the speed-up as well as the situation of distributions over supercomputing facilities in Japan.
<Keywords:> Fragment molecular orbital, FMO, ABINIT-MP, Supercomputer, A64FX, SX-Aurora TSUBASA
<URL:> https://www.jstage.jst.go.jp/article/jccj/20/4/20_2022-0001/_article/-char/ja/

[Published online Journal of Computer Chemistry, Japan Vol.20, 137-139, by J-STAGE]
<Title:> 第一原理計算によるカテキンの酸化還元電位の理論予測
<Author(s):> 段　練, 鷹野　優, 重田　育照
<Corresponding author E-Mill:> ytakano(at)hiroshima-cu.ac.jp
<Abstract:> Catechins are the main constituents in tea and have attracted attention due to their antioxidant properties. In this letter, the redox potential of single electron transfer and the pK_a of proton transfer in (+)-catechin has been calculated at the B3LYP/6-31++G (d, p) level of theory with a recently developed scheme to evaluate the standard hydrogen electrode potential and redox potential. Our computational scheme reproduced the experimental redox potential and pK_a value well.
<Keywords:> First-principles calculation, Catechin, Redox potential, Standard hydrogen electrode, p??i??K??/i????sub??a??/sub??
<URL:> https://www.jstage.jst.go.jp/article/jccj/20/4/20_2022-0002/_article/-char/ja/

[Published online Journal of Computer Chemistry, Japan Vol.20, 140-143, by J-STAGE]
<Title:> 動的分極率による励起状態計算へ向けた量子アルゴリズムqUCC-LR開発
<Author(s):> 高梨　倫哉, 吉川　武司, 中井　浩巳
<Corresponding author E-Mill:> nakai(at)waseda.jp
<Abstract:> In this study, we propose the quantum algorithm based on the unitary coupled cluster linear response theory for excited-state calculations with single and double excitations, denoted as qUCCSD-LR. Instead of the standard eigenvalue-problem-based scheme, the algorithm utilizes the dynamical-polarizability-based scheme, where the pole relative to the frequency of an external electric field corresponds to an excited state. Numerical applications of the qUCCSD-LR method to H₂ could reproduce the dynamical polarizabilities, excitation energies and oscillator strengths obtained by the standard CCSD-LR method. Furthermore, potential energy curves for the double bond rotation in the ground and excited states of C₂H₄ were accurately calculated by the proposed method.
<Keywords:> Quantum computer, Excited-state calculation, Unitary coupled cluster, Linear response, Dynamical polarizability
<URL:> https://www.jstage.jst.go.jp/article/jccj/20/4/20_2022-0007/_article/-char/ja/

[Published online Journal of Computer Chemistry, Japan Vol.20, 144-146, by J-STAGE]
<Title:> アミノ酸間相互作用ポテンシャルの類似度と分子構造の類似度の相関の解析
<Author(s):> 寺島　千絵子, 谷田　義明, 眞鍋　敏夫, 佐藤　博之
<Corresponding author E-Mill:> c.terashima(at)jp.fujitsu.com
<Abstract:> For middle molecule drug discovery, a coarse-grained model in which amino acid residues were treated with an amino acid pair interaction was investigated. To treat both natural and artificial types of amino acids and staples, new interaction potentials were developed by umbrella sampling. For any artificial types of amino acids, the amino acid its potential was similar enough was extracted by using our method applied the structure similarity.
<Keywords:> amino acid, Peptide, Coarse-grained model, Interaction potential, Molecular dynamics, Molecular similarity
<URL:> https://www.jstage.jst.go.jp/article/jccj/20/4/20_2022-0003/_article/-char/ja/