ABSTRACT:We introduce a new molecular theory beyond the Born᎐Oppenheimer approximation, where both electrons and nuclei are treated quantum mechanically and Ž . equivalently. First, we develop the coupled mean-field theory CMFT for both the electronic and nuclear fields. Then, to take into account the dynamic correlation between these particles, we develop a new molecular theory using the generator coordinate Ž . method GCM based upon the CMFT, which enables us to calculate the molecular eigenstate and eigenvalue directly. Finally, we apply this method to a water molecule and analyze the isotope effect on the vibrational frequency and the particle density.

The instabilities of a normal molecular orbital state of polyacenic materials are studied within RPA with a g model for an electronic interaction. The condensed states predicted are singlet superconducting (SSC), charge density wave (CDW), and spin density wave (SDW) ones, and their phase diagram is shown. In contrast to usual one-dimensional (1D) conductors, there reveals a wide range of superconducting state, which is not overcome by CDW transition. Weakness of Peierls distortion of the present model is also contrasted with the case of polyacetylene.

ABSTRACT:We present two cluster models of the active site of azurin. These models are determined by two stable configurations during our molecular dynamics (MD) simulation. In MD simulation, we find two stable configurations connected by the "jump motion" of Met121. One configuration is similar to the crystal structure by X-ray analysis, and the other is not the same. We perform density functional calculations for these two models and investigate physical properties such as total energy, singly occupied molecular orbital (SOMO), and spin density for each model. We find the difference in the shape of SOMO each other. We also estimate the reduction potential for each model and discuss the reduction potential and solvent effect of each model in relation to the electron transfer, which is one of the functionality of azurin.

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We investigate the superconductivity in a two-band model by using the renormalization group approach. We discuss the superconducting gap function in the two-band model.