| Research Abstract |
The aim of the present research was to develop an accurate electronic structure theory and a program package for large-scale systems, especially for the interface systems which consist of an active molecular part and the background giving environment to the active molecule. The focus was especially on the following topics : 1.Development of electron correlation methods for large-scale systems, in particular a multireference (MR) based perturbation theory (PT), 2.Development of relativistic methods for large-scale systems, 3.Development of an efficient program package including the electron correlation and relativistic methods, and 4.Studies on the electronic structure and chemical reaction of large-scale systems.
1.In the electron correlation method, an accurate and efficient scheme is essential. Utilizing the multireference perturbation scheme, we have developed a multiconfigurational perturbation theory with optimized Hamiltonian partitioning and a perturbation theory with the maximum
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radium of convergence. We have also presented Kohn-Sham DFT method with non-orthogonal localized orbitals.
2.In addition to the electron correlation effect, the relativistic effect is also important for the large-scale system including heavy atoms. We have developed four-component multireference perturbation (relativistic GMC-QDPT) and configuration interaction (CI) methods. Relativistic Gaussian basis sets for the use of these MRPT and MRCI methods were also proposed.
3.The methods have been implemented into an ab initio program package, UTChem.
4.With these electron correlation and relativistic methods, we have made the following applications to molecules including large-scale systems : the most stable structure of silicon-carbon clusters, templating effects on the mineralization of layered inorganic compounds, the electronic structure of long polyenes, the selective catalytic reduction of NO by ammonia, the structure and electronic excited states of merocyanine dyes, the chain oxydation reactions of methyl vinyl ether by OH radical, the photodissociation reaction of diketones, the excitation spectra of transition metal aqua complexes, and the excited state properties of N-confused porphyrin. Less
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