Six-dimensional calculation of intermolecular states in molecule-large molecule complexes by filter diagonalization: Benzene–H2O

Noncovalently bound molecular complexes beyond diatom–diatom systems: full-dimensional, fully coupled quantum calculations of rovibrational states

The methodological advances made in recent years have significantly extended the range and dimensionality of noncovalently bound molecular complexes for which full-dimensional quantum calculations of their rovibrational states are feasible.

Solvent configuration-interaction calculations of intermolecular states in molecule-(atom)N clusters: application to Br2-4HeN

We describe variational calculations of J=0 intermolecular states in Br(2)-(4)He(N) clusters. The method employed is analogous to configuration-interaction calculations in electronic-structure work and relies on the ability to express the intermolecular Hamiltonian H(v) as a sum of one- and two-body terms. A basis set is built up from solutions to the Schrödinger equation in which only the one-body terms of H(v) are included. These configurations are products of N=1 eigenstates. The matrix of H(v) in a symmetry-adapted configuration basis is then computed, the two-body terms of H(v) serving to couple different configurations. This computation involves integrals of dimension five or less. Filter diagonalization is then used to obtain energies and eigenfunctions within a selected energy range. Results on clusters having N=2-5 are reported.

Six-dimensional vibrational analysis of coupled intermolecular vibrations in a binary cluster

We report on full- (six-) dimensional calculations of the intermolecular vibrations of a binary aromatic-solvent cluster. An exact Hamiltonian for this kind of interaction is modified in a general manner in order to perform calculations of molecules without symmetry. The binary cluster phenol(H2O)1 is used as a test case since its intermolecular vibrations are anharmonic and highly coupled. The formulation of the Schrodinger equation leads to a complex-valued eigenvalue problem with a dimension larger than two million, which is solved by filter diagonalization to obtain both eigenvalues and eigenvectors. With the knowledge of the eigenvectors, an interpretation of all eigenvalues is possible by a characterization with pseudoquantum numbers that are related to the widely used nomenclature of intermolecular normal motions in aromatic(solvent) clusters.