# Sets of potentials, projectors, and pseudo-wave-functions

A given pseudopotential-generator code might offer several possible levels of theory, and output different sets of magnitudes accordingly.

The set attribute in several API routines allows the handling of various sets of semilocal pseudopotentials, projectors, and pseudo-wave-functions. Its value is normalized as follows, depending on the type of calculation generating the pseudopotential and the way in which the code chooses to present the results. (First, the symbolic name used in the API is given, followed by the value of the attribute in the PSML file)

• (SET_NONREL, non_relativistic) for the non-relativistic, non-spin-DFT case.

• (SET_SREL,scalar_relativistic) if the calculation is scalar-relativistic, or if it is fully relativistic and an set of lj potentials averaged over j is provided.

• (SET_SO, spin_orbit) if a fully relativistic code provides this combination of lj potentials.

• (SET_LJ,lj) for a fully relativistic calculation with straight output of the $lj$ channels.

• (SET_UP,up) and (SET_DOWN,down), for a spin-DFT calculation with straight output of the spin channels.

• (SET_SPINAVE,spin_average) for the spin-DFT case when the generation code outputs a population-averaged pseudopotential.

• (SET_SPINDIFF,spin_difference) for the spin-DFT case when the generation code outputs this (rare) combination.

Note that a given code might choose to output its semilocal-potential information in two different forms (say, as scalar-relativistic and spin-orbit combinations plus the lj form). The format allows this, although in this particular case the information can easily be converted from the lj form to the other by client programs.

For extensibility, the format allows two more values for the set attribute, (SET_USER1,user_extension1) and (SET_USER2, user_extension2), which can in principle be used to store custom information while maintaining structural and operative compatibility with the format.

The wildcard specification SET_ALL can be used to represent the union of all possible sets.