Jaeeon Chang

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The solvation free energies of amino acids and their side-chain analogues in water and cyclohexane are calculated by using Monte Carlo simulation. The molecular interactions are described by the OPLS-AA force field for the amino acids and the TIP4P model for water, and the free energies are determined by using the Bennett acceptance method. Results for the(More)
We have developed a general predictive method for vapor pressures and enthalpies of vaporization based on the calculation of the solvation free energy that consists of three components; the electrostatic, dispersion, and cavity formation contributions. The electrostatic contribution is determined using the quantum mechanical COSMO solvation model.(More)
We recently reported the COSMO-SAC-BP model for predicting vapor pressure and its temperature derivative, the enthalpy of vaporization. This COSMO-SAC-BP model, which contains no compound specific parameters, is based on determining three major solvation components: (i) an electrostatic contribution, calculated using the quantum mechanical COSMO(More)
The free energies of the orientationally ordered crystal phase of C60 at low temperatures and the disordered crystal phase at high temperatures are calculated to an accuracy of +/-0.05 kJ/mol using the expanded ensemble Monte Carlo method with the potential model of Sprik et al. [J. Phys. Chem. 96, 2027 (1992)]. The order-disorder transition temperature at(More)
Accurate values of the free energies of C60 and C70 fullerene crystals are obtained using expanded ensemble method and acceptance ratio method combined with the Einstein-molecule approach. Both simulation methods, when tested for Lennard-Jones crystals, give accurate results of the free energy differing from each other in the fifth significant digit. The(More)
We propose Lennard-Jones potential parameters for interatomic interactions of linear and branched alkanes based on matching the results of Gibbs ensemble simulations of vapor-liquid equilibria to experimental data. The alkane model is similar as in the OPLS-AA, but multiple atom types for carbon based on the number of covalently bonded hydrogen atoms are(More)
In this work, the chemical potentials of organic compounds in dense liquid phases are calculated by using expanded ensemble Monte Carlo simulations. To make insertion of a solute molecule efficiently, Lennard-Jones size parameters and bond lengths are varied with coupling parameter. A robust adaptive scheme is proposed in order to determine biasing weights(More)
We have studied the thermodynamic properties of hen egg white lysozyme crystals using a novel simulation method combining atomistic Monte Carlo simulation to calculate van der Waals interactions and the boundary element method to solve the Poisson-Boltzmann equation for the electrostatic interactions. For computational simplicity, we treat the protein as a(More)
Protein crystallization conditions are usually identified by empirical screening methods because of the complexity of the process, such as the existence of nonequilibrium phases and the different crystal forms that may result from changes in solution conditions. Here the crystallization of a model protein is studied using computer simulation. The model(More)
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