A Molecular Dynamics Study of the Structure of an LiCl • 3 H2O Solution

Abstract

The structure of an 18.5 molal aqueous LiCl solution has been investigated by MD simulation. The total radial distribution function from the simulation agrees reasonably well with that of an X-ray diffraction measurement. In the average each Li+ is in contact with one Cl-. Additionally, there are four water molecules in the first coordination sphere of Li+ which occupy preferentially octahedral positions. The hydration shell of Cl- is strongly disturbed by the formation of the contact ion pair. There is an almost complete breakdown of the water structure although the number of nearest neighbours is still four at the normal O - O distance in water. For the C1--C1- radial distribution a strong discrepancy exists between a neutron diffraction study with chloride isotope substitution and the simulation. All results are compared in detail whit recently published data from a simulation of a 13.9 molal LiCl solution.