Z1, Z2

These are the two forms of the Zetterling potential:[72]

V(r) = a$${\frac{{e^{\alpha r}}}{{r^3}}}$$cos(2kFr) + b$$\left(\vphantom{\frac{\sigma}{r}}\right.$$$${\frac{{\sigma}}{{r}}}$$$$\left.\vphantom{\frac{\sigma}{r}}\right)^{{n}}_{}$$ + V0.

(7)

Subroutines used: Z1 and Z2 etc. If three parameters are specified by the PARAMS keyword they are interpreted as box lengths for a periodic system.