Eisaku Miyoshi

Model potentials for molecular calculations. II. The spd‐MP set for transition metal atoms Sc through Hg

Model potential parameters and valence orbitals were generated for the transition metal atoms Sc through Hg. Only the nd and (n + 1)s valence electrons were treated explicitly and the effects of the remaining electrons were replaced by model potentials. For brevity they may be called sd‐MPs. Major relativistic effects were incorporated on the level of Cowan and Griffins quasirelativistic Hartree‐Fock (QRHF) method for the second and third transition metal atoms. The model potential parameters and valence orbitals were determined so as to reproduce the results of the numerical Hartree‐Fock reference calculations. The obtained valence orbitals have inner nodal structure. The model potential method can yield a balanced description of the s2dn–1, sdn, and dn + 1 configurations of the atoms. The polarization functions were also generated for the use in molecular calculations.

Electronic structure of small copper clusters. II. Localized d hole in excited states and ionized states of Cu2 and Cu3

The electronic structure of Cu2 and Cu3 clusters is investigated by ab initio SCF calculations. The geometry optimization is performed. Because of the Jahn–Teller effects the obtuse and acute isosceles triangle configurations of Cu3 are energetically lower than the regular triangle one. The ‘‘localized’’ orbital which is located at the top or center atom is commonly found through the obtuse, regular, acute, and linear triangle Cu3’s. The excited and ionized states where the localized d electron participates are energetically close to those of (s → s or s*) and (s → ∞) states, which suggests that the electronic structure of Cu3’s is similar to that of bulk. The calculated excitation energies and ionization potentials for these states agree with experiment within error of 1.0 eV. The localized d hole excited states and the ionized states are found in Cu2 as well. The effect of the basis set superposition on Cu2 and Cu3 and the band structure of larger Cu clusters are also discussed.

Theoretical study of the electron affinities of MF6 and MF 6- (M=Cr, Mo, and W) using a model potential method

Electronic structures of MF6, MF−6, and MF2−6 (M=Cr, Mo, and W) were calculated using a model potential method in the Hartree–Fock–Roothaan scheme. Major relativistic effects were taken into account for the calculations on MoFq6 and WFq6 (q=0, −1, and −2). It is shown that the calculated electron affinities (EAs) are extremely high for all the MF6 molecules, and that the CrF−6 and MoF−6 anions also have positive EAs, whereas the WF−6 anion has a slightly negative EA. The behaviors of the EAs are interpreted with reference to the electronic structures of the MFq6 systems.

On the electron affinities of hexafluorides CrF6, MoF6, and WF6

The adiabatic electron affinities (EAs) of MF6 and MF−6 (M=Cr, Mo, and W) are calculated in a configuration interaction (CI) calculation using a model potential method. The calculated EA of 3.85 eV for WF6 agrees well with the observed values. The difference (1.52 eV) between the calculated EA of MoF6 and that of WF6 shows also a very good agreement with the experimental ones. CrF6 has a very high EA of 8.24 eV. The CrF−6 anion has positive EA and the CrF2−6 dianion is thus most stable in the CrFq−6 (q=0, 1, and 2) sequence, while WF−6 does not have a positive EA. The EAs of MF6 calculated by CI calculations are smaller than those by SCF calculations. This negative correlation effect on the AEs is also discussed.

Model calculation for the frequency shift in CO coadsorbed with K on Cu(001)

The dramatic frequency shift recently observed for CO coadsorbed with alkali atoms on transition metals is analyzed by calculating the electronic structure of Cu12K2CO and by comparing it with that of Cu12CO, K2CO, CO−, and CO at the self-consistent Hartree-Fock model-potential level. The CO vibrational frequency in the coadsorbed system is reproduced by the calculation, and the frequency shift is elucidated: it is brought about by electron redistribution which leads to reduction of the overlap population between the C and O. The electron redistribution is caused mainly by an increase of electron flow into the 2π level due to a downward shift of this level because of direct interaction between CO and K.

Molecular orbital study of the interaction of hydrogen with Pd(111) surface

Abstract The electronic structure of the Pd 4 H cluster, which is a model of hydrogen adsorbed on the Pd(111) surface, has been investigated using Hartree-Fock calculations with a model potential method. The equilibrium H-surface distance is calculated to be 1.05 a.u. in the threefold site, which gives a Pd-H distance of 1.68 A. The potential energy barrier at the surface has a height of 0.15 eV from adsorption site. Gross charge on H is positive (+0.4 to +0.5), which is in contrast with results of semi-empirical calculations. The bonding is essentially between H 1s and Pd 4d, as will be shown in contour map of MO and overlap population. The calculated density of states (DOS) is also compared with photoelectron spectra. The calculated DOS explains most aspects of the observed spectra.