We derive the general fluctuation expressions for both the isothermal and adiabatic elastic constants of systems with arbitrary interparticle interactions and under arbitrary loading. We find that the expressions for these two kinds of elastic constants have exactly the same form though in general their values would be different. These formulas have the advantage that all elastic constants can be calculated in a single computer simulation run without performing any deformation on the system.
Relation:
Physical Review B (Condensed Matter and Materials Physics) 66(5), 54101(7pages)