Systematic Improvement of Energy-Components by Simultaneous Optimization of Exponents and Centers of Gaussian-Type Function Basis Sets for Molecular Self-Consistent-Field Wave Functions

Takayoshi ISHIMOTOa and Masanori TACHIKAWAb*

aINAMORI Frontier Research Center, Kyushu University
744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
bQuantum Chemistry Division, Graduate School of Science, Yokohama-City University
22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan

(Received: July 16, 2009; Accepted for publication: September 3, 2009)

Dedicated to the late Prof. Kazuhide MORI.

  We have applied the fully variational molecular orbital (FVMO) method to systematically improve the values of energy-components, that is, the kinetic energy of electron and potential energy, as with that of total energy. The FVMO method enables us to describe accurate values of energy-components, since the quantum-mechanical Virial and Hellmann-Feynman theorems are completely satisfied due to the optimization of the exponents and centers in Gaussian-type functions (GTFs) basis sets. In the calculation of H2 molecule, we have found that the energy components and total energy with FVMO method using only [6s] GTFs are actually improved more than those with the conventional MO using a much larger basis set including the multiple polarization functions of [6s3p2d1f]. Additionally, drastic improvement of virial ratios for several hydride molecules with the FVMO method is demonstrated in the current work. The energy-component analysis using the FVMO method would be a powerful tool to elucidate various chemical problems.

キーワード: Fully variational molecular orbital (FVMO) method, Energy-component analysis, Virial ratio, Hellmann-Feynman theorem, Optimization of exponent and center in Gaussian-type function (GTF)


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