XLAMBDA, XM, HOCHN -tags

$$XLAMBDA = \mbox{parameter $\lambda$\ for BHS pseudopotentials}$$

See equ. (2.12) in the paper of BHS [38]:

$$f^1(x) = f^2(x) = f^3(x) = {\rm e}^{-x^{\lambda}}$$

default is 3.5; default is rarely changed.

$$\begin{eqnarray*} XM &=& \mbox{parameter $m$\ for XNC pseudopotentials} \\ HOCHN &=& \mbox{parameter $n$\ for XNC pseudopotentials} \end{eqnarray*}$$

parameters used for the XNC (extended norm conserving) pseudopotentials, see equ. (11) in [40]:

$$f^3(x) = (1-mpx^n) 100^{- \sinh ^2(x/[1.5+(1-m)p]) / sinh^2(1)}$$ (54)

default is XM=0.5, and HOCHN=6; defaults are rarely changed.