We analyze the relativistic effects of the hyperfine coupling constant (HFCC) by using the solutions of the Dirac and Schrödinger equations of Hydrogen-like atoms. We find that the relativistic effects of HFCC of the ground states of the Hydrogen-like atoms (Z = 30, 40) are about 8% and 15%, respectively.

We have proposed a novel quantum chemical model to evaluate condensed-phase thermodynamic properties, that is, the harmonic solvation model (HSM). This paper explains the theoretical background of HSM and the practical procedure to use for the HSM with some sample inputs. Illustrative applications demonstrate the usefulness and accuracy of HSM.

A new and efficient approach for analyzing protein-ligand binding sites is proposed using a large number of properly interacting probe molecules with human coagulation factor Xa (fXa). Firstly, the probe molecules are set up to mimic the functional groups of the known ligand RRR, and cover the fXa surface by molecular dynamics (MD) simulation without water. Then, the unit cell is filled with water for following MD simulation to replace weakly binding probe molecules with water. The analyzed probe density explains well the experimental crystal structure of RRR whose terminal pyridine group is placed in the unexpected S4 pocket. This result indicates that the probe density evaluated from this approach has the ability to explain the binding orientation of a ligand.

We present a clear equation and a simple display method to analyze theoretically the spin density induced by an external static magnetic field in closed-shell molecules containing heavy atoms (Xe and HI). We showed that the magnitude of the spin density in a heavy-atom-light-atom (HALA) system is proportional to the mixing of the opposite spin orbital caused by the spin-orbit interaction.

By selectively investigating the effect of the bond valence using the hypothetical [(PO₄)W₁₂O₃₆]^3– species having various bond valences, we could clearly reveal the origin of the linear dependence of the LUMO energy (or the redox potential) on the bond valence. The LUMO of the Keggin-type polyoxotungstates mainly consists of W 5d. The energy of W 5d as well as of the LUMO goes down as the bond valence becomes large (i.e., as the net electron population on W decreases due to the electron-withdrawing effect of the μ₄-O atoms). This is the origin of the linear dependence of LUMO energy on the bond valence.

Koide’s equation was discovered for masses in the same sectors.

The mechanism of the mixed alkali effect of 0.25{xK₂O-(1−x) Na₂O}-0.75SiO₂ glasses was studied by using the molecular dynamics (MD) simulation. MD simulations of this work reproduced the mixed alkali effect. In addition, the tendency of molar volume with temperature change by this work was reproduced in the experimental tendency. The mixing of alkali was independent to the network structure of Si and O. The free volume in the glass systems indicated that high condensed packing occurred by alkali mixing. The results of ³⁹K¹³³KSi₃O₇ glass showed that the mass difference from one alkali metal ion decreased the diffusion of the other alkali metal ion. The mixed alkali effect was considered to relate to both the size- and the mass-differences of the coexisting alkali metal ions.

The (−)-podophyllic aldehydes (Figure 1) exhibit notable antineoplastic cytotoxicity by apoptosis-inducing activities. In this study, we analyzed the selectivity mechanisms of some important reactions in the asymmetric total synthesis of (+)-podophyllic aldehydes which are enantiomers of the (−)-podophyllic aldehydes, by the molecular orbital method. As a result, it was shown that the selectivity of the Grignard reaction in compound 1 (Figure 2) is caused by steric hindrance. Furthermore, it was also indicated that the selectivity of the reduction in compound 2–1 is caused by the localization of LUMO at the reactive site, and the reduction in compounds 2–2 and 2–3 (Scheme 2 ) does not proceed due to the steric hindrance by the trimethoxyphenyl group.

By using the Z-index a useful algorithm for obtaining such "dormant graphs" was discovered, which systematically generates pairs of isospectral tree graphs, although mathematical rigorousness is not yet completely attained.

We performed MD calculations on chloroform and 1,3,5-triamino-2,4,6-trinitrobebzene (TATB) and further frequency analysis under high pressure. Peaks around 3000 cm⁻¹ of chloroform uniformly blue shifted, but ones around 3000 cm⁻¹ of TATB were red shifted. It was concluded that whether hydrogen bonds are formed or not greatly influences the shift of the peaks of the two stretching vibrations.

Reactive force field parameters are re-optimized for simulating the stress corrosion cracking (SCC) of iron-based material in a supercritical water environment. The parameters for molecular dynamics (MD) simulation are determined by fitting the adsorption energies of H, OH, and H₂O on an Fe(110) surface obtained by reactive force field to the density functional theory (DFT) calculations. The errors of adsorption energies for the most stable positions are less than 5%, and our parameters are in good agreement with the DFT calculations. The development of Fe/O/H parameters is expected to contribute to SCC simulation of iron-based materials in supercritical water environments.

Electric double layer capacitor (EDLC) is a storage device based on the interfacial interaction between electrode and electrolyte. We have conducted molecular dynamics simulations to study the atomistic origin of storage capacity. Electric double layer structures are studied by changing the electric field applied to the electrolyte. Charge density distribution in the electrolyte phase derived on the basis of molecular dynamics simulation is used to discuss the capacitance-voltage characteristics for different electrolyte species.

Lithium air batteries are attracting attention as next generation secondary batteries because powerful secondary batteries are required for an application of electric vehicles. In the lithium air battery, Li₂O₂ is the main discharge product decomposed into Li⁺ and O₂ during charging, whereas electrochemically irreversible Li₂CO₃ and Li₂O are also formed. The reaction phenomenon of decomposition of these products is complex and influences the over potential during charging. The by-products decomposition and surface structure of the electrode also change the over potential. Therefore, decomposition behavior of discharge products on a cathode electrode during charging is fundamental in developing a high performance lithium air battery. In this study, we carried out a first principles molecular dynamics method (FPMD) with different electronic state to analyze the relationship between charging condition and decomposition behavior of discharge products on the carbon surface at the atomic level. In particular, the influence of the surface structure of the electrode on the dynamics of decomposition of Li₂O₂ was studied.