DIFFUSION OF TWO DIFFERENT WATER MODELS AND THERMAL CONDUCTIVITY IN A PROTEIN-WATER SYSTEM

摘要

The diffusion constant of dynamics simulation data evaluated by the time-dependent displacement or the velocity autocorrelation function provides equivalent results. The diffusion constant (D) increases with the cutoff distance for electrostatic energy. An extended version of the TIP3P water model provides a proper value of D at small cutoff distance (8.5 Angstrom); the SPC/E water model requires a larger cutoff distance (11.0 Angstrom). Considering Langevin dynamics with a total friction gamma, the Einstein relation (D similar to 1/gamma) is valid for large enough friction (gamma > 5 ps(-1)) only. Heating of a protein-water system by stochastic dynamics at the boundary is studied in detail. The calculated thermal conductivity of water agrees with experiment. The thermal conductivity of a protein molecule is about a factor of two smaller. (C) 1996 John Wiley & Sons, Inc. [References: 35]