A comment:
I'm not familiar with your increase RKmax until the "energy start to
increase again".
From what I have seen or read, you want to increase RKmax until the
"parameter you are interested in has converged". That parameter might
be total energy, EEL spectrum intensity, or another parameter.
For example, you might want to refer to Figure 1(b) in [1]. In the
figure, it can be seen that the total energy decreases rapidly as RKmax
increases from about 3.5 to 5.5 (i.e., has not converged). However, it
can be seen that the total energy has converged at about -302.5 Ry for
RKmax above 5.5. From this, they choose a suitable value of 7 for
RKmax. I suspect because RKmax of say 6 was too close to the transition
in energy (between non-convergence and convergence) and the slight
increase in accuracy of the energy for RKmax greater than 7 looks like
it was not worth the additional time needed to perform the calculations
(i.e., the shown increase in "time per scf cycle").
[1] R. J. Nicholls and A. J. Scott, Practical approaches to the accurate
modelling of EELS edges using density functional theory, J. Phys.: Conf.
Ser. 126, 012038 (2008). http://dx.doi.org/10.1088/1742-6596/126/1/012038
On 3/6/2015 6:43 AM, hannan.sa...@uv.es wrote:
To determine the suitable size of the basis set for the case that I'm
calculating.
Yes, you can increase RKmax as far as you want.
The question is: why would one want to do that ?
On 03/06/2015 10:10 AM, hannan.sa...@uv.es wrote:
Hello
I'm using the last version of WIEN2k. And it is explained in the user
guide that the best value of RKmax can be obtained by starting from the
recommended minimal value and then increasing it in steps of eg. 0.5
until we get the point at which the energy start to increase again as a
function of the used RKmax values. Also we have to note that the value
of RKmax cannot be set arbitrarily large and can't be lager than 11. So
my question is if I reached this value(Rkmax=11) and still don't have
the expected behavior of the energy(the energy doesn't start to increase
again)? can I use values larger than 11 in that case?
Best regards
Hannan
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