局所射影分子軌道法(Locally Projected Molecular Orbital)に基づく摂動論(LPMO PT)を発展させ、多数の分子間に働く非共有結合(non-covalent)相互作用を高速かつ高精度に計算する近似手法を開発し、分子クラスター研究に活用した。最も計算時間を要する部分をopenMPによる並列化し、水分子クラスター25量体の高精度計算を可能にした。LPMO PT法を分子クラスターのモンテカルロ(MC)シミュレーションに適用するプログラムMonte Carlo for Molecular Clusters by Python ((MC)2Py)を開発した。
The perturbation theory based on the Locally Projected Molecular Orbitals (LPMO PT) was developed to study the weak non-covalent molecular interaction. The LPMO PT successfully avoids the basis set superposition error (BSSE) by removing the orbital basis and configuration inconsistencies. Using the openMP, the time-consuming parts of the codes were parallelized, and the latest version of the code enables us to efficiently compute the binding energy of (H20)25 with the aug-cc-pVDZ basis set. The calculated relative binding energies of the isomers of (H20)n (n=6, 8, 13, 20 and 25) agree with those calculated with the more sophisticated and computation-demanding methods. One of the advantages of the LPMO PT is that the energy contribution from the charge-transfer and dispersion terms can be evaluated for every pair of the molecules in the large size of molecules. By utilizing these terms, the hydrogen bonded networks in water clusters are analyzed.

研究種目 : 基盤研究(C)
研究期間 : 2011～2013
課題番号 : 23550031
研究分野 : 理論化学･計算化学
科研費の分科・細目 : 基礎化学･物理化学