LMAXTAU = [integer]
Description: LMAXTAU is the maximum l-quantum number included in the PAW one-center expansion of the kinetic energy density.
The PAW one-center expansion of the density has component up to and including L=2*lmax, where lmax is the l-quantum number of the partial waves on the POTCAR file, with the highest angular moment. If the PAW one-center expansion of the density has component up to L, then the one-center expansion of the kinetic energy density has components up to L+2.
This means that as a rule of thumb, for s-elements: LMAXTAU=2, for p: LMAXTAU=4, and for d: LMAXTAU=6. If you are willing to live with the computational costs, the default for LMAXTAU should be safe in all cases, except those involving f-elements.