Selects the method that is used to calculate the DOS.
Currently not used for PDOS and LDOS.
Options:
smear:
Smearing with the smearing function selected by DOSSmearingFunction.
tetrahedra:
Linear tetrahedron method as in P. E. Bloechl, et al., Phys. Rev. B49, 16223 (1994).
Requires a regular Monkhorst-Pack generated by Octopus.
tetrahedra_opt:
Improved tetrahedron method as in M. Kawamura, et al., Phys. Rev. B89, 094515 (2014).
Requires a regular Monkhorst-Pack generated by Octopus.