MULTI-COMPONENT FIRST-PRINCIPLES CALCULATION ON ISOTOPE EFFECT IN HYDROGEN-BONDED DIELECTRIC MATERIALS K₃H(SO₄)₂ AND K₃D(SO₄)₂

ABSTRACT

We have theoretically elucidated the origin of the isotope effect on phase transition temperature in hydrogen-bonded ferroelectric materials K₃H(SO₄)₂ and K₃D(SO₄)₂, using the cluster models with multi-component molecular orbital (MC_MO) method, which can determine both electronic and nuclear wave functions simultaneously. We have confirmed that the origin of the isotope effect is the localization of the nuclear wave function by deuterization. We have also demonstrated the isotope effect in potential energies, geometrical structures, and electronic population on hydrogen nuclei.

Keywords:

• isotope effect on phase transition temperature
• hydrogen-bonded ferroelectric material
• geometrical isotope effect
• K₃H(SO₄)₂ and K₃D(SO₄)₂
• multi-component molecular orbital method
• ubbelohde effect

ACKNOWLEDGEMENT

The author would like to thank Grant-in-Aid for Scientific Research and for the priority area by Ministry of Education, Culture, Sports, Science and Technology, Japan and ENEOS Hydrogen Trust Fund.