Analysis of Exponent Values of Gaussian-Type Functions on Quantum Protons and Deuterons in Charged or Polarized Systems

作者：Hashimoto Marina; Ishimoto Takayoshi; Tachikawa Masanori^*; Udagawa Taro^*

来源：International Journal of Quantum Chemistry, 2016, 116(12): 961-970.

DOI：10.1002/qua.25117

• nuclear quantum effect
• multicomponent calculations
• H/D isotope effect

The optimal exponent alpha values (alpha(opt)) in s-type Gaussian-type functions (GTFs) for quantum protons and deuterons, which are used for multicomponent molecular orbital calculations including nuclear quantum nature of protons and deuterons, are analyzed for several charged or polarized systems and their deuterated species. Ishimoto and coworkers (Ishimoto, Int. J. Quantum Chem. 2006, 106, 1465) have already proposed the average exponent values for five neutral molecules (alpha(ave)), and demonstrated that their alpha(ave) enables us to evaluate the H/D isotope effect on energies and geometries of various neutral species. The differences between total energies of several charged or polarized systems with previous alpha(ave) and our alpha(opt) correspond to only less than 0.004% of the total energy (0.47 kcal.mol(-1)) except for HeH+ and HeD+ molecules, while the difference between interaction energies of H2OH+...OH2 and H2OD+...OH2 systems with previous alpha(ave) is 19% (0.22 kcal.mol(-1)) smaller than that with our alpha(opt). Meanwhile, the difference between OH bond lengths in H2OH+center dot center dot center dot OH2 system with alpha(ave) and alpha(opt) values is 0.027 angstrom. We also found that the interaction energies with alpha(opt) value at the geometry optimized with previous alpha(ave) value (alpha(sp)) well reproduce those at the geometry optimized with alpha(opt) value. We have demonstrated that the nuclear basis functions based on s-type GTFs with previous alpha(ave) values enable us to evaluate the H/D isotope effect on energies and geometries of charged or polarized systems.

• 出版日期2016-6-15