|if RPACOR 0||1|
Determines how the unscreening is done, and is used in conjunction with RPACOR (section 11.4.4). Usually the user must no set this flag by hand. It is saver to use RPACOR. If RPACOR is supplied IUNSCR will be set to 1 corresponding to a non linear unscreening. If RPACOR is not supplied or zero, IUNSCR will be set to 0 corresponding to a linear unscreening, and no partial core correction. IUNSCR = 2 uses Lindharts approach for the core-valence exchange correlation, this approach is only interesting in conjunction with pseudopotential perturbation theory and must not be used with VAMP.