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.