Accurate Numerical Computation of Rovibrational G Matrices in Molecules of Arbitrary Size

Conference Paper · June 2008with6 Reads
DOI: 10.1007/978-3-540-69839-5_77 · Source: DBLP
Conference: Computational Science and Its Applications - ICCSA 2008, International Conference, Perugia, Italy, June 30 - July 3, 2008, Proceedings, Part I

    Abstract

    In this work we present a methodology for the accurate numerical computation of the rovibrational G matrix in any molecule.
    A C++ program is developed to apply this methodology. Using polymorphism, the program can handle the output of any of the
    available electronic structure codes. The objective is to compute the kinetic contribution to the rovibrational Hamiltonian
    from the results of molecular structure scans, performed in heterogeneous and distributed systems such as Internet-based Grids
    of computers. The numerical derivatives needed to compute the G matrix in curvilinear, internal coordinates are obtained from
    an adapted Richardson extrapolation. The procedure is optimized to maximize the number of significant digits in the derivatives.
    Using the program, we compute the vibrational kinetic terms for several simultaneous torsional motions in Glycolaldehyde,
    Methyl formate and Ethyl methyl ether. The results show the existence of an important coupling among the torsional vibration
    modes.