Paper title:
Comparison of simple potential functions for simulating liquid water
Journal:
J. Chem. Phys. 79, 926 (1983)
Author/s:
William L. Jorgensen1, Jayaraman Chandrasekhar1, Jeffry D. Madura1, Roger W. Impey2, and Michael L. Klein2
[1] Department of Chemistry. Purdue University. West Lafayette. Indiana 47907
[2] Chemistry Division. National Research Council of Canada. Ottawa. Canada KIA OR6
Summary:
This paper compared the results of Monte Carlo (MC) simulations of water dimer that used six different intermolecular potential functions to experimental results containing thermodynamic and structural data. The water models compared were Bernal-Fowler (BF), SPC, ST2, TIPS2, TIP3P, and TIP4P. Each of these six potential functions has a rigid water monomer that is represented by three, four or five interaction sites. The MC simulations for liquid water were done using the NPT ensemble at 250C and 1 atm.
The calculated properties which were compared to experimental data were density, intermolecular energy, heat of vaporization, heat capacity, thermal diffusivity, and coefficient of thermal transfer. The water models were also compared to self-diffusion coefficients obtained from molecular dynamics simulations.
Densities and potential energies were computed for each of the water model. It was found that all but the original BF model was in agreement with experiment. Errors in densities for SPC, TIP3P, TIPS2, TIP4P, and S2 were 3%, 2%, 7%, 0%, and 7%, respectively.
The structure of liquid water for different potential functions, which is provided by radial distribution functions (RDF) and partial structure functions, was obtained through diffraction experiments. TIPS2 and SPC potentials have the closest agreement with experiment in terms of oxygen-oxygen RDF. TIP4P was also quite good but it showed a little shift in peak positions. RDFs for OH and HH were almost similar for all computed results. For oxygen-oxygen partial structure functions, only TIPS2 and TIP4P potentials were in accordance with results from neutron diffraction. However, even though all six potentials produced similar results for hydrogen-hydrogen and hydrogen-oxygen partial structure functions, all of them exhibited poor accordance with neutron diffraction results.
It was concluded that SPC, ST2, TIPS2, and TIP4P could give reasonable structural and thermodynamic descriptions of liquid water. Moreover, SPC, TIPS2, and TIP4P were better for computations because of their simplicity. Overall, TIPS2 and TIP4P were the most promising among the water models studied here because of their superiority in different aspects studied.
Contribution and application:
Based on this paper, we can choose which water model would be good for our lab’s simulations. And as it turned out, TIP4P and TIPS2 were the 2 best potentials available. Since TIP4P is already available in LAMMPS, it can be the water model appropriate for our lab’s research. It was mentioned that TIP4P would be good for simulations of aqueous solutions, and that would be NaCl solutions which we can use to study desalination. Moreover, this paper can be used as a main reference for our research when it comes to water models because the authors provided the necessary parameters that we need to provide in our LAMMPS input scripts to represent water.
By: Hannah Ebro
hannah@gist.ac.kr