[Wien] Semi core band-ranges too large while finding best Rmt*Kmax

[Marcelo Barbosa]

Dear Sirs,

While trying to find the best Rmt*Kmax value for Ga2O3 following the procedure done by S. Cottenier in this document "http://www.wien2k.at/reg_user/textbooks/DFT_and_LAPW_2nd.pdf”, my simulation stops with the following error

 LAPW2: semicore band-ranges too large

when Rmt*Kmax is equal to 9.00 and using the command run_lapw -cc 0.000001.

Looking into the .error files, I get

 'LAPW2' - semicore band-ranges too large, ghostbands ?

The .scf1 output gives me the following values for the energies

          ATOMIC SPHERE DEPENDENT PARAMETERS FOR ATOM  Ga1       
:e__0001: OVERALL ENERGY PARAMETER IS    0.1930
          OVERALL BASIS SET ON ATOM IS LAPW
:E0_0001: E( 0)=    0.1930
             APW+lo
:E0_0001: E( 0)=  -10.0138   E(BOTTOM)=  -10.065   E(TOP)=   -9.963  2  3   153
             LOCAL ORBITAL
:E1_0001: E( 1)=    0.1930
             APW+lo
:E1_0001: E( 1)=   -6.4077   E(BOTTOM)=   -6.516   E(TOP)=   -6.300  1  2   138
             LOCAL ORBITAL
:E2_0001: E( 2)=   -0.5997   E(BOTTOM)=   -0.987   E(TOP)=   -0.212  0  1   145
             APW+lo
:E2_0001: E( 2)=    0.5930
             LOCAL ORBITAL

          ATOMIC SPHERE DEPENDENT PARAMETERS FOR ATOM  O 1       
:e__0003: OVERALL ENERGY PARAMETER IS    0.1930
          OVERALL BASIS SET ON ATOM IS LAPW
:E0_0003: E( 0)=   -0.6691   E(BOTTOM)=   -2.066   E(TOP)=    0.728  1  2   241
             APW+lo
:E0_0003: E( 0)=    0.5930
             LOCAL ORBITAL
:E1_0003: E( 1)=    0.1930
             APW+lo

 and the .scf2 output gives me this warning

:WARN :BAN00001:   1  -13.912696  -10.003657  2.00000000


The energy values in .scf1 for the APW+lo and for the LO in all orbitals are very far apart, so I suppose the problem isn’t here.

My RMT values are set by setrmt_lapw using a 3% reduction, which gives 1.75 for Ga and 1.59 for O, so I think they are not very different from one another.

I know that Rmt*Kmax = 9.0 is very high, but when comparing the :ENE and :EFG values from Rmt*Kmax = 8.5 to Rmt*Kmax = 8.0, I get differences of 0.01 in :ENE and 0.02 in :EFG, which are a little bit higher than I wanted to, so I would like to try bigger Rmt*Kmax values to see if I get smaller differences.

Is there a way to solve this error and do the calculation using this value of Rmt*Kmax or is this value too high for this structure and thus I’m not supposed to go this high?
I suppose the error might disappear if I reduce the RMT’s manually (or use and equal value for both atoms), but shouldn’t I use the values given by setrmt_lapw since in this case they are not that far apart?
If reducing RMT’s solves the problem, what’s the best procedure for doing calculations: using the best Rmt*Kmax value allowed for the RMT’s given by setrmt_lapw or setting RMT’s manually until we can find the value of Rmt*Kmax which results in a better convergence?

Thank you very much in advance for your help.

Best regards,
Marcelo


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