High-rank quantum topological electrostatic potential: Molecular dynamics simulation of liquid hydrogen fluoride

Five bulk properties of liquid hydrogen fluoride were obtained by a molecular dynamics simulation at five temperatures between 203 and 273 K. The rigid-body interaction potential was designed with emphasis on the electrostatic contribution. The potential was expanded in spherical tensor multipole moments, and its corresponding Ewald summations, containing all possible interaction up to L=5 (i.e., monopole–hexadecapole, dipole–octopole, quadrupole–quadrupole). The moments were generated by a quantum chemical topological analysis of the electron density of the geometry-optimized monomer at the MP2/aug-cc-pVTZ level. Only two parameters in the Lennard-Jones part of the potential were adjusted to the experimental density and radial distribution functions. Agreement with experiment is excellent for the total energy and the density, and reasonable (with even overall performance) for the diffusion coefficient, the isobaric heat capacity and the thermal expansion coefficient. Chains of hydrogen-bonded HF monomers up to 10 molecules are quite common in the liquid and they more or less retain the relative orientation of the HF monomers in the gas-phase dimer.