In order to understand the electronic, dynamics and spectroscopic features of trace gases in the atmosphere, we have performed the following projects: (1) We construct next-generation molecular theory for real systems, and develop an integrative theoretical chemistry program package, “UTChem”. We have developed the following theory; a multiconfigurational many-body perturbation theory (GMC-QDPT) where the parent electron configurations are selected in accordance with the character of a system, a regional self-interaction correction scheme that improves underestimated chemical reaction barriers in DFT calculations, a high-speed computational algorithm of the 4-component Dirac equation, and so forth. (2) Propagation delay of signals by interlayer dielectrics in LSI interconnects is becoming a dominant issue. Materials of low dielectric constant have been widely studied in order to reduce the delay of signals. In this study we try to design theoretically novel low-k materials based on ab initio quantum chemical methods and the density functional perturbation theory (DFPT). (3) We report semiclassical energy spectra of vibrational state of a cluster composed of 7 identical atoms in terms of our previously developed semiclassical wave function, which we call the action-decomposed function. The classical dynamics of this vibrational state is strongly chaotic and undergoes a large amplitude motion due to structural isomerization, which demands a long run of trajectory calculation.
Next-generation molecular theory, Theoretical chemistry program package “UTChem”, interlayer dielectrics, low-k materials, cluster, vibrational spectrum, chaos