During the self-consistent field (SCF) cycle the essential data are appended to the file case.scf in order to generate a summary of previous iterations. For an easier retrieval of certain quantities the essential lines are labelled with :LABEL:, which can be used to monitor these quantities during self-consistency as explained below. The most important :LABELs are
:ENE total energy
:FORxx force on atom xx
:DIS charge distance between last 2 iterations (sum of difference
densities)
:DTOxx total difference charge density for atom xx between last
2 iterations
:CTOxx total charge in sphere xx
:QTLxx partial charges in sphere xx
:FER Fermi energy
:EFGxx Electric field gradient Vzz for atom xx
:ETAxx Asymmetry parameter for atom xx
:NEC normalization check of electronic charge densities. When
a significant amount of electrons is missing, one might have
core states, whose charge density is not fully confined within
the respective atomic sphere and these states should be treated
as band states (using LOs).
For spin-polarized calculations:
:CHA Total magnetic moment/cell, which can be determined from
the difference of the spin-up and spin-down charges (shown in
two consecutive lines)
:CUPxx spin-up charge in sphere xx
:CDNxx spin-dn charge in sphere xx (the approximative magnetic
moment of atom xx can be estimated from the difference CUP -
CDN)
:HFFxx Hyperfine field of atom xx (in kGauss).
One can monitor the energy eigenvalues (listed for the first k-point only), the Fermi-energy or the total energy. Often the electronic charges per atom reflect the convergence. Charge transfer between the various atomic spheres is a typical process during the SCF cycles: large oscillations should be avoided by using a smaller mixing parameter; monotonic changes in one direction suggest a larger mixing parameter.
In spin-polarized calculations the magnetic moment per atomic site is an additional crucial quantity which could be used as convergence criterion.
If a system has electric field gradients and one is interested in that quantity, one should monitor the EFGs, because they are very sensitive quantities.
It is best to monitor several quantities, because often one quantity is converged, while another still changes from iteration to iteration. The script run_lapw has three different convergence criteria built in, namely the total energy, the atomic forces and the charge distance (see 5.1.2, 5.1.3).
We recommend the use of UNIX commands like :
grep :ENE case.scf or use ``Analysis'' from WIEN in a BOX
for monitoring such quantities.
You may define an alias for this (see sec. 11.2), and a csh-script grepline_lapw is also available to get a quantity from several scf-files simultaneously (sec. 5.2.8 and 5.3).