Question

how to find lattice energy any shortcut tricks. plz sggst me guyz

Answer 1

Comparing lattice energies (enthalpies) obtained from a classical force field and ab initio calculations is certainly one way to validate the former. In this case you would run two sets of simulations: one with the solid phase, as you suggest, and one with isolated particles (e.g., ideal gas). The difference between enthalpies of the crystal and ideal gas would be the lattice energy (enthalpy). Depending on your subject, there may be more appropriate ways test a force field. If you are interested in solutions rather than crystals, comparing lattice energies may not be the most informative test. Solvation free energies and enthalpies along with diffusion coefficients may give you a better idea.