  Molecular dynamics simulation is a prominent way of analyzing the dynamic
properties of a system. The molecular dynamics simulation of diffusion, an
important transport property, of dilute solution of cysteine in SPCE water at
five different temperatures (288 K, 293 K, 303 K, 313 K, 323 K) under the
pressure of 1 bar is studied using GROMACS. OPLS AA force field parameters are
used throughout the simulation. The system under study consists of 3 cysteine
molecules (mole fraction 0.003) as solute and 1039 water molecules (mole
fraction 0.997) as solvent. The radial distribution functions (RDFs) for five
different combinations of atoms of solvent-solvent and solute solvent molecules
are studied for structural analysis. At least two or more distinct peaks are
observed in RDFs plots implying that there are interactions between atoms of
solvent solvent and solute solvent at least up to two co ordination shells. The
self diffusion coefficients of solute and solvent are determined exploiting
mean square displacement (MSD) in Einsteins equation. The self diffusion
coefficients are used to calculate the binary diffusion coefficients by means
of Darkens relation. The calculated values of self diffusion and binary
diffusion coefficients are compared with available experimental values and they
agreed within 12 percent. The temperature dependency of diffusions are
demonstrated via Arrhenius plots and with the help of these plots activation
energies for diffusions are calculated which agreed with experimental results
within 13 percent.
