pwtools.eos.ElkEOSFit.get_min

ElkEOSFit.get_min(behave='new')

Calculate properites at energy minimum of E(V).

Parameters:

behave (str, optional, {'new', 'old'})

Returns:

• behave = ‘new’ (return a dict {v0, e0, p0, b0}) – volume, energy, pressure, bulk modulus at energy min

• behave = ‘old’ (array of length 4 [v0, e0, b0, p0])

Notes

We have two sources for pressure: (a) The code which calculated E(V), i.e. usually some ab initio code (PWscf, …). (b) Calculated pressure P=-dE/dV from the EOS fit to E(V). If the (a) pressure at the E(V) minimum is not very close to zero (say ~ 1e-10), then your E-V data is incorrect. Usually, this is because of poorly converged calculations (low cufoff / bad basis set, too few k-points).