RESEARCH ACTIVITIES I
Department of Theoretical Studies

A. Development of New Theoretical and Numerical Techniques in the Study of Molecular Structures

  1. Superposition of Nonorthogonal Slater-Determinants towards Electron Correlation Problems
  2. Theoretical Studies of the Dipole Bound Anions of Molecular Clusters and the Photo-detachment Cross Section with Hybrid Basis Sets of Gaussian Functions and Plane Waves
  3. Static Structure Factor and Electron Correlation Effects Studied by Inelastic X-ray Scattering Spectroscopy
  4. Construction of Two Electron Reduced Density Matrix for Static Structure Factor Calculation

B. Hybrid Procedures of Ab Initio MO Calculations and Monte Carlo Samplings

  1. Theoretical Prediction of Intracluster Reactions of B+(H2O)2 and B+(H2O)3 Clusters: Hybrid Calculations of Ab Initio MO and Monte Carlo Samplings
  2. Ab Initio Monte-Carlo Simulation Using Multi-Canonical Algorithm: Application to Water Dimer

C. Structures and Reactions of Atomic and Molecular Clusters

  1. Structures of Water Cluster Anions
  2. Intracluster Reaction Dynamics of Argon Tetramer Ions
  3. Ab Initio MO Studies of Si4NO+
  4. Ab Initio Study of Photochemical Reactions of Ammonia Dimer Systems
  5. Theoretical Studies of Cyclic Radicals NOx (x=2-6)
  6. Six -Membered Rings Nx O6-x (x=0-5): Theoretical Examination of the Stability
  7. Ab Initio MO Studies of Neutral and Anionic SiCn Clusters (n=2-5)
  8. Geometric and Electronic Structures of Silicon-Sodium Binary Clusters: Ionization Energy of SinNam
  9. Ab initio studies on the structures, vertical electron detachment Energies and stabilities of CnP- clusters
  10. Theoretical Study of the Structure and internal motion of (N2)2 Cluster

D. Structures and Vibrational Frequencies of Infinite Polymer Chains

  1. Density Functional Crystal Orbital Study on the Normal Vibrations of Poly-acetylene and Polymethineimine
  2. Density Functional Crystal Orbital Study on the Normal Vibrations and Phonon Dispersion Curves of All-Trans Polyethylene

E. Accurate Studies of Low-Lying States of Diatomic and Triatomic Molecules

  1. Portrait of Diatomic FeN. A Theoretical Study
  2. A Theoretical Study of the Electronic Structure and Spectroscopic Properties of the Low-Lying Electronic States of the Molecule SiB
  3. Ab Initio Calculations for Potential Surfaces of HNO

F. Application of Ab Initio Molecular Orbital and Density Functional Methods to Experimentally Relevant Systems

  1. Comparative Ab Initio and Hybrid DFT Studies Relevant to An Experimental Investigation of Neutral and Cationic [Si,P,H2] Isomers
  2. Ab Initio Study of the Isomers: HNNSi, HSiNN, and HNSiN
  3. The Ground and Low-Lying Excited States of the Phenyl Cation C6H5+: Revisited
  4. Ab Initio MO and Density Functional Studies on the Vibrational Spectra of 1,4-Benzoquinone, and Its Anion and Dianion
  5. Ab initio Study of Internal Rotation of Methyl Groups in Toluene Derivatives
  6. Local Hard-Soft Acid Base Principle: A Critical Study
  7. An Ab Initio MO Study of Esa(1-para-methoxy-stylbene) and Its para-Alogen Substituents: A Model of Interdigitated Organization Within the Smectic Layer

G. Prediction of Protein Tertiary Structures from the First Principles

  1. Monte Carlo Simulations in Generalized Ensemble: Multicanonical Algorithm versus Simulated Tempering
  2. Numerical Comparisons of Three Recently Proposed Algorithms in the Protein Folding Problem
  3. Calculation of Hydration Free Energy for a Solute with Many Atomic Sites Using the RISM Theory: Robust and Efficient Algorithm
  4. Solvation Structure and Stability of Peptides in Aqueous Solutions Analyzed by the Reference Interaction Site Model Theory
  5. A Simple Ansatz to Describe Thermodynamic Quantities of Peptides and Proteins at Low Temperatures
  6. Characteristic Temperatures of Folding of a Small Peptide
  7. Tertiary structure prediction of C-Peptide of ribonuclease A by multicanonical algorithm
  8. First-Principle Determination of Peptide Conformations in Solvents: Combination of Monte Carlo Simulated Annealing and RISM Theory
  9. Calculation of Solvation Free Energy for a Peptide in Salt Solution Using the RISM Theory
  10. Electrostatic Effects on the alpha-Helix and beta-Strand Folding of BPTI(16-36) as Predicted by Monte Carlo Simulated Annealing
  11. Effective Parameters for Solvation Energy of Proteins Based on Solvent Accessible Surface Area
  12. Classification of Low-Energy Conformations of Met-Enkephalin with Hydrophobic Interactions Based on the Scaled Particle Theory Taken into Account

H. Development of Simulation Algorithms for Complex Systems

  1. Generalized-Ensemble Monte Carlo Method for Systems with Rough Energy Landscape
  2. Simulated Annealing with Tsallis Weights --- A Numerical Comparison
  3. An Effective Way for Determination of Multicanonical Weights
  4. A New Look at the 2d Ising Model from Exact Partion Function Zeros for Large Lattice Sizes
  5. Parallel Tempering Algorithm for Numerical Studies of Biological Macromolecules
  6. Molecular Dynamics, Langevin, and Hybrid Monte Carlo Simulations in Generalized Ensemble

I. Theoretical Studies of Chemical Reaction Dynamics

  1. Quantum Dynamics of O(3P) + HCl -> OH + Cl: Effects of Reagent Rotational Excitation
  2. Hyperspherical Elliptic Coordinates for the Theory of Light Atom Transfer Reactions
  3. Quantum Mechanical Elucidation of Reaction Mechanisms of Heavy-Light-Heavy Systems: Role of Potential Ridge
  4. Cumulative Reaction Probability without Absorbing Potentials

J. Theory of Nonadiabatic Transitions

  1. Semiclassical Theory of Multi-Channel Curve Crossing Problems: Landau-Zener Case
  2. Usefulness of the Newly Completed Semiclassical Theory of Curve Crossing: Multi-Channel Resonant Scattering
  3. Semiclassical Theory of Multi-Channel Curve Crossing Problems: Nonadiabatic Tunneling Case
  4. Semiclassical Theory of Time-Dependent Curve Crossing Problems
  5. Exact Analytical Solution of the N-Level Landau-Zener Type Bow-Tie Model
  6. Semiclassical Theory of Nonadiabatic Transition in a Two-State Exponential Model
  7. Semiclassical Mechanics of Cubic Potentials

K. Theoretical Studies of Characteristics and Dynamics of Superexcited States of Diatomic Molecules

  1. Characteristics and Dynamics of Superexcited States of Diatomic Molecules
  2. Two-Center of Coulomb Functions
  3. Gausian Expansions of the Two-Center Coulomb Functions

L. New Molecular Switching Elements

  1. Molecular Switching in One-Dimensional Finite Periodic Nonadiabatic Tunneling Potential Systems

M. Rydberg States in External Fields

  1. Rydberg Atom in Time-Periodic Fields: Intrashell Dressed States and Quasienergy Spectrum

N. Some Basics of Scattering Theory

  1. Siegert Pseudo-States as a Universal Tool: Resonances, S-Matrix, Green Function
  2. Flux Formulations of Scattering Theory

O. Fokker-Planck Equation Approach to Quantum Dynamics in Condensed Phases

  1. Gaussian-Markovian Quantum Fokker-Planck Approach to Nonlinear Spectroscopy of a Displaced Morse Potentials System: Dissociation, Predissociation and Optical Stark Effects
  2. Fifth-Order Two-Dimensional Vibrational Spectroscopy of a Morse Potential System in Condensed Phases

P. Path integral Approach to Nonlinear Optical Spectroscopy of Molecules in the Condensed Phase

  1. Sensitivity of Two-Dimensional Fifth-Order Raman Response to the Mechanism of Vibrational Mode-Mode Coupling in Liquid Molecules
  2. Interplay of Inhomogeneity and Anharmonicity in 2D Raman Spectroscopy of Liquids
  3. Coherent Two-Dimensional Raman Scattering: Frequency-Domain Measurement of the Intra- and Intermolecular Vibrational Interactions
  4. Two-Time Correlation Functions of a Harmonic System Nonbilinearly Coupled to a Heat Bath: Spontaneous Raman Spectroscopy
  5. The Optimized Perturbation Theory to Femtosecond Vibrational Spectroscopy of a Diatomic Molecule System in Condensed Phases

Q. Theoretical Studies of Molecular system coupled to nonGaussian-Markovian Environment

  1. Spectral Random Walks and Line Broadening of Impurity Molecules in an Ising Spin Glass Environment
  2. Effects of Colored Noise Bath on the Spectra of a Strongly Driven Two-Level System

R. Electronic Structure of a Molecule in Solution

  1. Ab initio Study of Water: Self-consistent Determination of Electronic Structure and Liquid State Properties
  2. Molecular Theory of Solvent Effect on keto-enol Tautomers of Formamide in Aprotic Solvents: RISM-SCF Approach

S. Solvation Thermodynamics of Protein and Related Molecules

  1. Analysis on Salt Effects on Solubility of Noble Gases in Water Using the Reference Interaction Site Model Theory
  2. Calculation of Hydration Free Energy for a Solute with Many Atomic Sites Using the RISM Theory: Robust and Efficient Algorithm
  3. Ion Hydration: Thermodynamic and Structural Analysis with an Integral Equation Theory of Liquids
  4. Solvation Structure and Stability of Peptides in Aqueous Solutions Analyzed by the Reference Interaction Site Model Theory
  5. Calculation of Solvation Free Energy for a Peptide in Salt Solution Using the RISM Theory
  6. First-Principle Determination of Peptide Conformations in Solvents: Combination of Monte Carlo Simulated Annealing and RISM Theory

T. Spatial and Temporal Density Fluctuation in Molecular Liquids

  1. Shear-Induced Distortion of Intramolecular and Intermolecular Correlations in Liquids: Time-Dependent Density-Functional Theory
  2. Statistical Mechanics of Deformable Molecular Liquids: Thermal Expansion and Isomerization of Diatomic Molecules
  3. Nonlinear Electrical Potential Fluctuations of Solvent around Solutes: an Integral Equation Study
  4. Interaction-Site Representation for Collective Excitations in Diatomic Dipolar Liquid
  5. Theoretical Study for Water Structure at Highly Ordered Surface: Effect of Surface Structure

U. Theoretical Studies of Low-Dimensional Correlated Electron Systems

  1. Various Transitions in Quasi-One-Dimensional Systems under High Pressure
  2. Phonon Effects on Superconducting Phase in Two-Chain Electron Systems
  3. Renormalization-Group Approach to the Metal-Insulator Transitions in (DCNQI)2M (DCNQI is N,N'-Dicyanoquinonediimine and M=Ag, Cu)
  4. Spin Gap of S=1/2 Heisenberg Ladder: Field Theoretical Study of Magnetic Susceptibility and NMR Relaxation Rate
  5. Nuclear Gaussian Spin Echo Decay in S=1/2 Heisenberg Ladder
  6. Spin Fluctuations in Magnetically Coupled Bilayer Cuprates
  7. Quantized Conductance of One-Dimensional Doped Mott Insulator
  8. The Effect of Electron Interaction on the Coherence Length of Polymer
  9. Electron Correlation and SDW in Polymer
  10. Off-Diagonal Interation, Bond Density Correlation, and Their Effects on the Excitons in Conjugated Polymers

V. Theoretical Studies of Superconductors under Magnetic Field

  1. Quasi-Particle Band Structure and Gapless Superconductivity in the Vortex-Lattice State

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