rfms1 [lfms1 nscmt ca nmix]
This card controls FEFF's automated self-consistent potential
calculations. Thus all fields except rfms1 are optional.
If this card is not specified, then all calculations are done with the
non-self-consistent (overlapped atomic) potential.
By default lfms1=0, nscmt=30, ca=0.2, and
This specifies the radius of the cluster
for full multiple scattering during the self-consistency loop.
Typically one needs about 30 atoms within the sphere specified by
rfms1. Usually this value is smaller than the value rfms
used in the FMS card, but it should be larger than the
radius of the second coordination shell.
The default value 0 is appropriate for
solids; in this case the sphere defined by rfms1 is
located on the atom for which the density of states is calculated.
The value 1 is appropriate for molecular calculations and will
probably save computation time, but may lead to inaccurate
potentials for solids. When
the center of the
sphere is located on the absorbing atom.
This is the maximum number of iterations
the potential will be recalculated. A value of 0 leads to
non-self-consistent potentials and Fermi energy estimates. A value of
1 also yields non-self-consistent potentials but the Fermi energy is
estimated more reliably from calculations of the DOS.
Otherwise, the value of nscmt sets an
upper bound on the number of iterations in the self-consistency
loop. Usually self-consistency is reached in about 10 iterations.
The convergence accelerator factor. This
is needed only for the first iteration, since FEFF uses
the Broyden algorithm to reach self-consistency. A typical value
is 0.2; however, you may want to try smaller values if there are
problems with convergence. After a new density is calculated from
the new Fermi level, the density after the first iteration is
is extremely unstable and should not be used.
This specifies how many iterations to do
with the mixing algorithm before starting the Broyden algorithm.
The SCF calculations in materials containing f-elements may not converge.
We encountered such a
problem for Pu. However, the SCF procedure converged if we started the
Broyden algorithm after 10 iterations with the mixing algorithm with
. nmix must be between 1 and 30; a value
outside of this range will be ignored, and replaced with an acceptable
* Automated FMS SCF potentials for a molecule of radius 3.1 Angstroms
SCF 3.1 1
* To reach SCF for f-elements and UNFREEZEF we sometimes had to use
SCF 3.7 0 30 0.05 10