University of MichiganAnn Arbor, MI 48109-2143

Department of Atmospheric, Oceanic and Space Sciences

Department of Chemistry

MultiWell Program Suite

John R. Barker, N. F. Ortiz, J. M. Preses, L. L. Lohr, A. Maranzana, P. J. Stimac, T. L. Nguyen, and T. J. Dhilip Kumar


Contact

This is the MultiWell web site. Contact John R. Barker at jrbarker@umich.edu for further information or to be added to the email list.

NEW IN VERSION 2010 (Jan. 2010) and 2010.1 (Feb. 2010)

Changes to adensum

  1. Bug fix: a minor bug in rare cases (for some molecules) was found to interfere with the initialization. This bug has been fixed.

Important New Capabilities

  1. Densities of states for anharmonic, non-separable vibrations. Three different practical algorithms/programs for calculating densities of states for fully-coupled, non-separable vibrations have been added to the MultiWell Program Suite. This new capability is an important advance beyond separable models, which up until now were the standard for RRKM and master equation calculations. The three algorithms are compared with each other and with accurate benchmarks in a new manuscript, which has been submitted for publication (available by request).

    • Program doloops: exact counts of states for small molecules (3-4 atoms)
    • Program adensum: an automated version of the Wang-Landau (and Basire et al.) random walk algorithm for computing approximate sums and densities of states. Appropriate for most molecules (≳4 atoms).
    • Program ansum: uses an "efficient" Monte Carlo algorithm for computing approximate sums and densities of states. Appropriate for small molecules (3-6 atoms).
  2. New code: Program lamm: computes the effective mass (or reduced moment of inertia) for large amplitude motions as a function of the internal coordinate (e.g. dihedral angle). This implementation of lamm is for non-rigid hindered internal rotation. The results are used with the "flexible" hindered internal rotor option (type hrd, which is already available in DenSum and Thermo) for computing sums and densities of states (DenSum) and thermodynamic functions (Thermo)from the energy eigenvalues, which are obtained by diagonalizing the quantum Hamiltonian. In future, we plan to extend program lamm and the eigenvalue solutions to inversion modes and ring puckering.
  3. New script: gauss2lamm.sh: this script reads Gaussian output files and automates (in part) creation of the data file for lamm.
  4. Starting with this version, the MultiWell User Manual, the Examples, and the compressed package of computer codes are down-loaded separately. This is to reduce the size of the individual compressed files.

Changes to MomInert

  1. Bug fix: due to a bug in a Fortran write statement, the rotational constants (i.e. Ba, Bb, and Bc) for the external rotations were too large by a factor of 10, while the moments of inertia (i.e. Ia, Ib, and Ic) were correct. This bug has been fixed.