Showing papers by "Kwang S. Kim published in 1991"
TL;DR: In this paper, the authors performed HF-SCF calculations on several structures of the water hexamers which are expected to have low-lying energies in the potential energy hypersurface and showed that the hexamer with the global minimum energy has the structure of the cyclic oxygens with S 6 symmetry.
75 citations
TL;DR: In this article, the two degenerate components of the ground electronic state give rise to independent minima (of 2A and 2A' symmetries) upon interaction with the water molecule.
Abstract: The two degenerate components of the OH radical 2Π ground electronic state give rise to independent minima (of 2A‘ and 2A’ symmetries) upon interaction with the water molecule These two minima have been investigated here for the first time using ab initio quantum mechanical methods Minimum, double zeta, double zeta plus polarization, and triple zeta plus double polarization basis sets have been employed in conjunction with self‐consistent‐field, second‐order perturbation, and configuration interaction methods At all levels of theory, the 2A‘ state is predicted to be the global minimum, with a dissociation energy De of about 35 kcal/mol The 2A’ state is predicted to lie about 1 kcal higher in energy Both minima occur for structures with OH⋅⋅⋅O linkages close to linear and are reminiscent of the water dimer However, the H⋅⋅⋅O distances (∼21 A for 2A‘, ∼22 A for 2A’) are significantly longer than observed for the water dimer Preliminary estimates of the H2O⋅OH vibrational frequencies are made
64 citations
Journal Article•
TL;DR: In this paper, the effect of solvents and counterions in Z-DNA crystal of d(5Brc-G-5BrC-G -5Br cg-G −5Br Cg-5br cg -G-G) was studied and the local energy analysis was performed.
Abstract: To study the effect of solvents and counterions in Z-DNA crystal of d(5BrC-G-5BrC-G-5BrC-G), we performed the local energy analysis and then molecular dynamics simulations. Since counterions raise serious caging problems in crystal simulations, it is very important to search for the possible positions before simulations. For this purpose, the local energy analysis was done for the whole crystal volume. It is shown from our simulation that counterions along with water molecules play a bridging role to bind adjacent oligomers so as to form the crystal. In this crystal, each water molecule bound to Gua-N2H, either directly or indirectly, hydrates the adjacent anionic phosphate oxygen, and thus assists Gua to be in a syn position. From the simulation, the average root-mean-square deviation of allthe DNA heavy atom coordinates from the X-ray data is . The bases are less deviated from the X-ray positions than the phosphates. The temperature factors from the simulation are consistent with those from the X-ray refinement, showing that the phosphates are more mobile than the bases.
2 citations