Papers by Keyword: Molecular Orbital Method

Abstract: The molecular orbital approach to alloy design is reviewed in this paper. This approachis based on the electronic structure calculations by the DV-Xα cluster method. New alloyingparameters are obtained for the first time by the calculations of titanium alloys and used for theprediction of phase stability and alloy properties. For example, it is shown that any titanium alloycan be classified into either the α, or α+β, or β type from the alloy composition by using the newalloying parameters. The corrosion resistance is also treatable along this approach. This theoreticalapproach is useful for the practical design of biomedical titanium alloys.

Abstract: A molecular orbital approach to alloy design has recently made great progress. Single crystal Ni-based superalloys and high Cr ferritic steels have been developed following this approach. Some perspectives will also be described on the design of heat resistant alloys.

Abstract: The electron density distributions in a series of metal oxides are calculated using the DV-Xα molecular orbital method. It is found that the logarithm of the electron density, logρ(r), decreases with the distance, r, from the oxygen nucleus, while keeping a constant slope relevant to oxygen atom. The magnitude of the slope is about 15.75 for O-1s electrons, and about 6.61 for O-2s, 2p electrons, being nearly close to the respective values of 16 and 8, expected from the radial distribution functions of hydrogen-like atom containing only one electron. The extent of the region for the O-2s, 2p electrons changes with metal species in the oxides, but the slope remains unchanged. Furthermore, it is shown that the nature of the chemical bonding is well represented in log (ρ _minZ-3) vs. 2(Z/n) r_{minb plots, where ρmin is the minimum electron density, rmin is the distance r at ρmin, Z is the atomic number, and n is the principal quantum number.}

Abstract: A molecular orbital approach to alloy design has recently made great progress. This approach is based on the electronic structure calculations by the DV-Xα molecular orbital method. New PHACOMP and the d-electrons concept have been constructed and applied to alloy design. Recently, nickel-based single crystal superalloys for power generation gas turbine blades and high Cr ferritic steels for turbine rotors have been developed successfully with this approach.