emass -fictitious mass of the electronic degrees of freedom
DESCRIPTION
The emass variable can be used to override the default value
of the fictitious mass of the electronic degrees of freedom (see wf_dyn). When emass is set to zero (the default),
GP will use a fictitious mass value derived from the values of the ecut and dt variables through
the expression
emass = 2 * ecut * dt2This value normally ensures stability of the algorithms used to update wavefunctions. The value chosen automatically can be printed using the status command, and is listed under "automatic emass value". In some rare cases (e.g. very large unit cells, when starting an electronic energy minimization) this value was found to cause instabilities. If this happens, the value of emass should be set to a value larger than the automatic value.
The emass variable must be specified in atomic units of mass, in which the mass of an electron is 1, and the mass of a proton is 1823.
DEFAULT VALUE
0
ALLOWED VALUES
non-negative floating point
RELATED INFORMATION