[Wien] thebest rkmax

[bs bs]

Hello
I work on b-Ga2O3 and want find the best rkmax for later computation
I read  Density Functional Theory andthe Family of (L)APW-methods.
 I set rmt automatically 3 percent and I find the best kpoint=1500 and for
finding RKmax  I draw ENE and EFG DIAGRAM WITH THREE METHOD:  LAPW ,
APW+lo( only for d orbital)   ,APW+lo
It is data

      RKMAX
 EFG-3-1500-apw-lo-d
 RKMAX
 EFG-3-1500-LAPW
 RKMAX
 EFG-3-1500-apw-lo
 6.5
 -10.46302
 6.5
 -10.44725
 6.5
 -10.93648
 7
 -10.52736
 7
 -10.49163
 7
 -10.85745
 7.5
 -10.55091
 7.5
 -10.51129
 7.5
 -10.80085
 8
 -10.5587
 8
 -10.5176
 8
 -10.7541
 8.5
 -10.41831
 8.5
 -10.39793
 8.5
 -10.57499
 9
 -10.39471
 9
 -10.37109
 9
 -10.52883

         rkmax ENE-3-1500-apw-lo-d rkmax ENE-3-1500-LAPW rkmax
EFG-3-1500-apw-lo 6.5 -16455.84767 6.5 -16455.45887 6.5 -16455.9337 7
-16456.16668 7 -16455.97715 7 -16456.20075 7.5 -16456.32583 7.5 -16456.23768
7.5 -16456.33914 8 -16456.40439 8 -16456.36533 8 -16456.40935 8.5
-16456.44358 8.5 -16456.42731 8.5 -16456.4456 9 -16456.46448 9 -16456.45858
9 -16456.46626l
EFG and ENE diagram of LAPW  and all of EFG diagram converge 8.5--9
but EFG diagram of LAPW and APW+lo(d)  first drop monotonically until
rkmax=8 then start going up and then in 8.5-9 coverge again
why?
can I choose the best rkmax=8.5 or I must choose rkmax in 6-8?
is the best method APW+lo in this case?why?
please guid me
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