Calculating thermoelasticity with LAMMPS

According to LAMMPS’s documentation, there are three ways to compute the thermoelastic tensor in general:

  1. The Born-matrix method
  2. The stress-strain method
  3. The triclinic cell fluctuations that occur in an NPT simulation (seems difficult to converge)

The Born-matrix method

The elastic stiffness tensor is related to the Born matrix tensor by (Clavier et al., 2017; Krief & Ashkenazy, 2021)

where and are given by

In LAMMPS, the Born matrix is calculated using the compute born/matrix command.