Theoretical study of the H/D isotope effects on the binding of a positron to polyatomic molecules

2016 Fiscal Year Final Research Report

• Project/Area Number: 26410020
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: Yokohama City University
• Principal Investigator: Kita Yukiumi 横浜市立大学, 生命ナノシステム科学研究科(八景キャンパス), 准教授 (40453047)
• Co-Investigator(Renkei-kenkyūsha): TACHIKAWA Masanori 横浜市立大学, 生命ナノシステム科学研究科, 教授 (00267410)
• Research Collaborator: TAKEDA Yu 横浜市立大学, 生命ナノシステム科学研究科 ; FUJIOKA Osamu 横浜市立大学, 生命ナノシステム科学研究科 ; NAKAYAMA Ryota 横浜市立大学, 生命ナノシステム科学研究科 ; URAKAWA Umihiro 横浜市立大学, 生命ナノシステム科学研究科
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 陽電子 / 陽電子親和力 / H/D同位体効果 / 振動励起 / 量子モンテカルロ法

Outline of Final Research Achievements

In order to elucidate the mechanism of H/D isotope effect on the binding of a positron to polyatomic molecules theoretically, we have developed a new anharmonic vibrational state theory based on quantum Monte Carlo method, and have applied our theory to the hydrogen cyanide and formaldehyde molecules. Analyzing positron affinities (PA), which is the binding energy of a positron to molecules, at vibrational excited states, we found (i) a negative H/D isotope shift on the PA value for hydrogen cyanide molecule, and (ii) a positive H/D isotope shift for formaldehyde molecule. We also confirmed that the physical origin of such isotope effects is mainly the change in the permanent dipole moments by vibrational excitations.

Free Research Field

理論化学・計算化学