Abstract
We elucidated the nuclear quantum effect on the intermolecular hydrogen bond of the acetic acid − phosphorous acid anion cluster system, a model system of periplasmic phosphate binding protein (PPBP) which is reported to have a low barrier hydrogen bond (LBHB), employing a multiscale parallel program platform for highly efficient simulation on high performance computers developed by combining a molecular science program NTChem and path integral molecular dynamics (PIMD) method. We analyzed the model system with one intermolecular hydrogen bond and found that the proton in the hydrogen bond is localized to heavy atoms on both ends as seen in typical hydrogen in the classical simulation, treating the nucleus with classical point charges. On the other hand, the proton delocalized in the center region of the hydrogen bond was found in the quantum simulation taking nuclear fluctuation effect into account. The intermolecular hydrogen bond in the acetic acid − phosphorous acid anion cluster system showed the same tendency with LBHB.
