[Wien] re-useing previous charge density gives strange total energy

[Hu, Qing Miao]

Dear WIEN2K users,

I tested the Rmt*Kmax values for the case of Cu by using different
procedures. But the total energies given by these prodedures differed
significantly from each other. Examples are given as the following:

            Procedure 1: Initialize the calculation for each Rmt*Kmax,
i.e., use the charge density genearated by 'x dstart' for each Rmt*Kmax.
This procedure gave a total energy of -3310.010662 Ry for Rmt*Kmax=6,
-3310.061286 Ry for Rmt*Kmax=8, and -3310.064521 Ry for Rmt*Kmax=10;

            Procedure 2: As suggested in the WIEN2K mannual, save the
results of the calculation for small Rmt*Kmax by using the SAVE command,
change the Rmt*Kmax to larger one, and then re-calculating. This
procedure gave a total  energy of -3310.057559 Ry for Rmt*Kmax=8 and
-3310.051423 for Rmt*Kmax=10, which are obviously unreasonable.

            Procedure 3: make a new directory for larger Rmt*Kmax, only
copy the nessesary input files (*.in0, *.in1, *.in2, *.inm, *.inc,
*.struct, *.klist) and the converged charge density for small Rmt*Kmax
to this directory, change the Rmt*Kmax to larger one. This prodedure
gave results colse to Prodedure 2.

For all the SCF calculation in the three procedures, the charge density
converged to 0.0001.

I hope that the problem was resulted from some stupid things I did in
the calculation, and I will be very grateful if someone could help me to
find which stupid things I did. Otherwise, it may implicate that the SCF
calculation is dependent on the initial charge density, which is
dangerous becuase there maybe losts of WIEN2K users use Procedure 2 or 3
in order to save computation time.

By the way, I also tested the K mesh by using both Procedure 1 and 2,
and both gave reasonable results.

Sincerely yours,
Qing Miao Hu

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Dr. Qing Miao Hu
Fritz-Haber-Institut der Max-Planck-Gesellschaft
Faradayweg 4-6, D-14195 Berlin-Dahlem, Germany
Tel: +49 30 8413 4815
Fax: +49 30 8413 4701
E-mail: qmhu at FHI-Berlin.MPG.de
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