I wish to use LJ potential for aluminium. what epsilon and sigma values should I use. Kindly suggest.
Dear Dr. Navjot Kaur,
The LJ potential for epsilon and sigma depends on what specific model of aluminum you are trying to simulate. (I, myself, simulate polymers using the Kremer-Grest parameters for epsilon and sigma.)
Epsilon is the bond energy (amount of energy necessary to escape pairwise attraction)
Sigma is the effective diameter of the aluminum atom since LJ potential is zero when distance r is equal to sigma. When the pairwise distance r is smaller than sigma, the repulsive force becomes larger and larger due to Pauli Exclusion Principle hence you are invading the space occupied by the atom’s sphere of influence.
It is hard to provide advice unless you inform more details of your aluminum model.
Thank you.
Sincerely,
Masato Koizumi
Navjot,
The best place to find LJ parameters (or any other type of parameters) for any material is the literature. A Google search for “LJ potential for aluminium” gave me this paper which compares LJ and EAM potentials for predicting bulk modulus of aluminum: https://www.jmaterenvironsci.com/Document/vol9/vol9_N1/11-JMES-3344-Chabba.pdf. They also use LAMMPS for their MD simulations.
By the way, the LAMMPS mailing list is for issues related to LAMMPS specifically, not general MD advice.
Best Regards,
Will