HD isotope effect on the dihydrogen bond of NH+4...BeH2 by ab initio path integral molecular dynamics simulation.

Quantum Chemistry Division, Graduate School of Science, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan.
The Journal of Chemical Physics (Impact Factor: 3.12). 12/2006; 125(20):204310. DOI: 10.1063/1.2388257
Source: PubMed

ABSTRACT In order to investigate the HD isotope effect on a dihydrogen bonded cation system, we have studied NH+4...BeH2 and its isotopomers by ab initio path integral molecular dynamics. It is found that the dihydrogen bond can be exchanged by NH+(4) rotation. The deuterated isotopomer (ND+(4)...BeD(2); DD) can exchange the dihydrogen bond more easily than other isotopomers such as (NH+4...BeH2; HH). This unusual isotope effect is ascribed to the "quantum localization" which occurs when the effective energy barrier for the rotational mode becomes higher by the zero point energy of other modes. We also found that the binding energy of dihydrogen bonds for DD species is the smallest among the isotopomers.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The partial isotope substitution for the change of geometrical parameters, interaction energies, and nuclear magnetic shielding tensors (σ) of dihydrogen-bonded NH3 X(+) ···YBeH (X, Y = H, D, and T) systems is analyzed. Based on the theoretical calculation, the distance between heavy atoms RN···Be of NH3 H(+) ···DBeH is clearly found to be shorter than that in NH3 D(+) ···HBeH. Such apparently paradoxical geometrical isotope effect (GIE) on RN···Be is revealed by the cooperative effect of two kinds of (1) primary covalent-bonded GIE and (2) secondary dihydrogen-bonded one. We have demonstrated that (1) the covalent bond lengths become shorter by heavier isotope-substitution and (2) the dihydrogen-bonded distance RX···Y becomes shorter by heavier Y and lighter X isotope-substitution due to the difference of electronic structure reflected by the nuclear distribution. We have also found that interaction energy of NH3 H(+) ···DBeH is stronger than that of NH3 D(+) ···HBeH and isotopic deshielding effect of magnetic shielding becomes large in lighter isotope. © 2013 Wiley Periodicals, Inc.
    Journal of Computational Chemistry 12/2013; · 3.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have developed an ab initio path integral molecular dynamics method based on the fragment molecular orbital method. This “FMO-PIMD” method can treat both nuclei and electrons quantum mechanically, and is useful to simulate large hydrogen-bonded systems with high accuracy. After a benchmark calculation for water monomer, water trimer and glycine pentamer have been studied using the FMO-PIMD method to investigate nuclear quantum effects on structure and molecular interactions. The applicability of the present approach is demonstrated through a number of test calculations.
    Journal of the Physical Society of Japan 10/2009; 78:104723. · 1.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Temperature dependence on the structural fluctuations of Zundel cation, H5O2 (+), and its isotopomers, D5O2 (+) and T5O2 (+), have been studied using path integral molecular dynamics simulations in which nuclear quantum effect is fully taken into account. It has been found that the fluctuations of hydrogen-oxygen and oxygen-oxygen distances, which are relevant to the hydrogen bonded structure, grow drastically as the temperature increases within the range of investigation between 100 K and 900 K. The fluctuation with respect to the position of non-bonded hydrogen also increases substantially as the temperature increases. The temperature dependence on the fluctuation is greater for D5O2 (+) or T5O2 (+) than that of H5O2 (+), since the zero-point effect of the former is less than the latter.
    The Journal of Chemical Physics 05/2013; 138(18):184307. · 3.12 Impact Factor


Available from
May 22, 2014