Extending correlation functions of molecular dynamics simulation by Kovalenko–Hirata and Kobryn–Gusarov–Kovalenko closures for monatomic Lennard-Jones solvent and its application to a calculation of solvation

We have tried to extend the short-ranged radial distribution function of the molecular dynamics (MD) simulation for a monatomic Lennard-Jones solvent by applying the Ornstein–Zernike theory with two hybrid closures. One was the hybrid with the Kovalenko–Hirata or the KH closure (hybrid MD–KH closure), whereas the other was the hybrid with the Kobryn–Gusarov–Kovalenko or the KGK closure (hybrid MD–KGK closure). As long as the switching distance between the MD and the KH (or the KGK) is chosen appropriately, the direct correlation functions obtained by these hybrid closures were almost identical to each other, which also agree with those of the hybrid closure with the hypernetted chain or the HNC (hybrid MD–HNC closure). The calculations on the solute–solvent correlation function and the solvation free energy also supported the practical equivalence among the hybrid MD–KH, hybrid MD–KGK, and hybrid MD–HNC closures.