Biomedical subjects

Hiroshi Tatewaki

Publications and source records attributed to Hiroshi Tatewaki.

8 recordsLinked to original sources

PubMed2006

Gaussian-type function set without prolapse for the Dirac-Fock-Roothaan equation (II): 80Hg through 103Lr.

We present prolapse-free universal Gaussian-type basis sets for 80Hg through 103Lr. The basis set is determined so that the Dirac-Fock-Roothaan total energy should decrease monotonically toward the numerical Dirac-Fock total energy. The difference between the Dirac-Fock-Roothaan total energy and the numerical Dirac-Fock total energy is less than 3 x 10(-6) hartree for 1H through 102No, and less than 5 x 10(-6) hartree for 103Lr. The exponents of the present sets are determined in an even-tempered manner, aiming to give total energy closer to the numerical Dirac-Fock value as the expansion term increases. The recommended set is expanded by (64, 64, 64, 46, 46, 46, 46) terms for (s+, p-, p+, d-, d+, f-, f+) symmetries, respectively. A practical set with (56, 48, 48, 36, 36, 36, 36) terms is also presented.

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PubMed2006

Electronic structure of the GdF molecule by frozen-core four-component relativistic configuration interaction calculations.

The electronic structure of GdF is calculated based on frozen-core four-component relativistic configuration interactions. The resulting excitation energies are fairly close to experiment and correctly designate the excited states. For instance, the existence of the experimentally inferred state at 0.55 eV above the ground state is confirmed, having Omega=132 with (4f(7)5d(+) (1)6s(+) (1)); it is 0.58 eV above the ground state according to the present calculation.

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PubMed2006

A study of the ground state of manganese dimer using quasidegenerate perturbation theory.

We study the electronic structure of the ground state of the manganese dimer using the state-averaged complete active space self-consistent field method, followed by second-order quasidegenerate perturbation theory. Overall potential energy curves are calculated for the 1Sigmag+, 11Sigmau+, and 11Piu states, which are candidates for the ground state. Of these states, the 1Sigmag+ state has the lowest energy and we therefore identify it as the ground state. We find values of 3.29 A, 0.14 eV, and 53.46 cm(-1) for the bond length, dissociation energy, and vibrational frequency, in good agreement with the observed values of 3.4 A, 0.1 eV, and 68.1 cm(-1) in rare-gas matrices. These values show that the manganese dimer is a van der Waals molecule with antiferromagnetic coupling.

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PubMed2005

Correlation energies for He isoelectronic sequence with Z=2-116 from four-component relativistic configuration interactions.

The relativistic correlation energies (CEs) for the He isoelectronic sequence from 2He to 116Uuh were investigated using configuration-interaction (CI) calculations. We used a large universal-type Gaussian basis set, which gives accurate Dirac-Fock total energies for the ions under consideration. In contrast to nonrelativistic CEs, the relativistic CEs decrease monotonically with increasing nuclear charge, but the p-, d-, and f-partial CEs have a hump like the relativistic Hylleraas CI.

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PubMed2005

Characterization of molecular orbitals by counting nodal regions.

The number of nodal regions can be used as an index for characterizing molecular orbitals. A computer program has been developed to count the number of nodal regions, based on the labeling and contraction algorithms. This program is applied to the water molecule, the hydrogen sulfide molecule, the hydrogen atomic orbitals, the Rydberg excited states of ethylene, dissociation of carbon monoxide, and CASSCF calculations of formaldehyde. Because the number of nodal regions is independent of the coordinate system, the method is applicable even when the molecular structure changes drastically as in bond rotation or bond elongation. Changes of nodal regions with bond elongation are investigated for carbon monoxide. A prescription for problems arising with basis set expansion techniques is also given.

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PubMed2004

Gaussian-type function set without prolapse 1H through 83Bi for the Dirac-Fock-Roothaan equation.

We have developed prolapse free Gaussian basis sets which can be used for 1H to 83Bi, imposing the condition that the Dirac-Fock-Roothaan (DFR) total energy (TE) decreases monotonically toward the numerical DF (NDF) TE as the expansion term increases. An even-tempered basis set was assumed. The resulting sets gave |TE(DFR) - TE(NDF)| < or = 1 x 10(-6) hartree for any atoms less or equal to 83Bi; TE(NDF) = -21 565.638 345, and TE(DFR) = -21,565.638 345 +/- 0.000 001 hartree for Bi when the expansion terms are in the range (58, 58, 58, 36, 36, 36, and 36) and (72, 72, 72, 36, 36, 36, and 36) for (s+, p-, p+, d-, d+, f-, and f+) symmetries, respectively. A practical set with 44, 44, 44, 36, 36, 32, and 32 for the respective symmetries is also proposed where |TE(DFR) - TE(NDF)| < or = 4 x 10(-5).

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PubMed2004

Quality of contracted Gaussian-type function basis sets.

The valence quality of contracted (C) Gaussian-type function (GTF) basis sets in molecular calculations is discussed for the first- through fourth-row atoms. The split-valence basis sets derived from minimal-type CGTF sets are compared with those derived from primitive (P) GTF sets. Using F, Cl, Br, and I atoms and their homonuclear diatomics as test species, we find that the split-valence CGTF sets have almost the same quality as PGTF sets with larger s and p expansion terms: for example, the (53/5), (533/53), (5333/533/5), and (53 333/5333/53) CGTF sets correspond approximately to the [9/5], [15/9], [19/15/5], and [22/18/7] PGTF sets for the first- to fourth-row atoms, respectively, where the slash separates the s, p, and d symmetries. For the main group atoms of the four rows, we recommend using the above-mentioned CGTFs or larger.

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PubMed2003

Gaussian-type function set without prolapse for the Dirac-Fock-Roothaan equation.

A Gaussian-type function (GTF) set without a prolapse (variation collapse) is generated for the Dirac-Fock-Roothaan (DFR) equation. The test atom was mercury. The number of primitive GTFs used is between 7 and 62 (abbreviated as 7-62), 6-62, 6-62, 4-36, 4-36, 3-36, and 3-36 for s(+), p(-), p(+), d(-), d(+), f(-), and f(+) symmetries. The respective exponent parameters were determined with even-tempered manner, which requires the minimum and maximum exponents for the respective symmetries. We prepared several sets of these. The total energy (TE) given by the numerical DF (NDF) is -19648.849250 hartree; one of the present sets with largest number of expansion terms gave -19648.849251 hartree. The error (deltaTE) relative to the NDR TE is quite small. We then applied this set to the inert gas atoms Ne (10), Ar (18), Kr (36), Xe (54), Rn (86), and No (102), and also to Es (99) as the representative of the open shell atoms. The absolute values of deltaTE were at most 2.8 x 10(-6) hartree, showing the potential of this set as a universal set.

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