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[zfhou@mail.edu.cn]

Dear abinit users,

Because I want to do the RP calculations of cubic HfO2, I first do some 
"stupid" calculations to know the effect of some variables like diemac, 
toldfe, tolvrs and tolwfr on convergence of GS.

In three test calculations, diemac is increased from 3 to 15 in step of 2, 
meanwhile toldfe, tolvrs and tolwfr are kept as 1.0d-8, 1.0d-19 and 1.0d-18 
for each case. I found that for all values of diemac, the GS calculations are 
converged for toldfe less than 1.0d-8 and tolvrs less than 1.0d-19 within 30 
steps. But for tolwfr=1.0d-18, the GS calculation is not converged within 60 
steps and the tolwfr is about 1.0d-6 at the 60th step.  

In addition, I also do the test calculation that when I use tolwfr=1.0d-18 I 
let the code read the converged wavefunction and charg density from GS 
calculations(in which i use tolvrs=1.0d-19). It isn't converged within 60 
steps for tolwfr=1.0d-18 yet. The tolwfr is still about 1.0d-6 at the 60th 
step. 

In the manual of abinit, there are these sentences to explain tolwfr:
 "Note that the preparatory GS calculations before a RF calculations must be 
highly converged.  Typical values for these preparatory runs are tolwfr 
between 1.0d-16 and 1.0d-22. "

My questions are:
1). What is the range of tolwfr to be set for GS calculations before RP 
calculations for diffrent cases(metal, molecule, semicondutor and insulator) 
indeed? and for the ddk-RP calculations?
2). Since there are some convergence problem with tolwfr, can tolwfr be 
replaced in ddk-RP calculations and the GS calculations befor RP-calculations 
if one get accurate RP calculation?
3). How to make calculations to be converged when use tolwfr? Is there any 
rule-of thumb?

Your helps and comments will be greatly appreciated!

Best wishes!
zhufeng 

btw, I also tested the calculations for Si. It's OK for using tolwfr=1.0d-19. 
I used Hartwigsen-Goedecker-Hutter LDA psp for test calculations of cubic 
HfO2.

---------------one of my input files-----
# Crystalline cubic HfO2 

  ndtset  6

diemac: 3.0       
diemac+ 2.0 
      
#Ground state calculation
      

#Definition of the unit cell
acell  9.5071208040E+00  9.5071208040E+00  9.5071208040E+00
#angdeg 90.0  90.0  90.0
rprim  0.0  0.5  0.5    
       0.5  0.0  0.5    
       0.5  0.5  0.0   

#Definition of the atom types
#spgroup  225
ntypat 2    
znucl 72  8           
natom 3           
typat 1 2*2        
xred             
   0.0  0.0  0.0  
   1/4  1/4  1/4 
   3/4  3/4  3/4 
  
#Definition of the k-point grid
                
 kptopt   1                 
ngkpt 6 6 6       
nshiftk 4        
                
shiftk 0.5 0.5 0.5
       0.5 0.0 0.0
       0.0 0.5 0.0
       0.0 0.0 0.5

#Definition of the SCF procedure
ecut  35.0   
iscf   3      
nstep 60          
tolvrs 1.0d-18       
nband 60
ixc  2
localrdwf 1
----------------END--------------