[Pw_forum] spilling parameter

Gabriele Sclauzero sclauzer at sissa.it
Tue Mar 2 17:51:12 CET 2010


Dear Dimpy,

    either there are two users of this forum who share the same name and affiliation or 
you do not receive/read some of the replies from the forum.

Just one week ago I replied to the same question in another thread you've opened:

[Pw_forum] summation of total PDOS does not matches the Total DOS


Here it is:

Dimpy Sharma wrote:
 > >
 > > Hi quantum espresso users,
 > >
 > > The summation of all the projected  density of states is not matching
 > > the total density of states at higher energy.I repeated my calculationby
 > > reducing the number of bands. I got a spiiling parameter of 0.0174. My
 > > system is Si and H.Can anyone please tell me , where can I get some
 > > refrences about the spilling parameter .I used the following parameters

The best source of information is to look inside the code. For instance:

[sclauzer at hg1 espresso-4.1.2]$ grep spilling PP/*.f90
PP/projwfc.f90:  ! calculates Lowdin charges, spilling parameter, projected DOS
PP/projwfc.f90:     ! The spilling parameter measures the ability of the basis provided by
PP/projwfc.f90:     ! The spilling parameter measures the ability of the basis provided by
PP/projwfc.f90:     ! The spilling parameter measures the ability of the basis provided by

and inside the file you'll find the reference:
...
       psum = SUM(charges(:,:,:)) / nelec
       WRITE( stdout, '(5x,"Spilling Parameter: ",f8.4)') 1.0d0 - psum
       !
       ! Sanchez-Portal et al., Sol. State Commun.  95, 685 (1995).
       ! The spilling parameter measures the ability of the basis provided by
       ! the pseudo-atomic wfc to represent the PW eigenstates,
       ! by measuring how much of the subspace of the Hamiltonian
       ! eigenstates falls outside the subspace spanned by the atomic basis
       !
       DEALLOCATE (charges)
...


HTH

GS

 > >   etot_conv_thr = 1.D-4
 > >    forc_conv_thr = 1.D-3
 > >            nstep = 600
 > >           wf_collect = .true
 > >
 > >        ecutwfc = 40
 > >       ecutrho = 160.0
 > >    diagonalization ='david'
 > >         mixing_mode = 'plain'
 > >            conv_thr = 1.0d-6
 > >         mixing_beta = 0.3
 > >
 > > Thanks and regards
 > >
 > > Dimpy
 > >
 > > UCC,Ireland
 > >

Dimpy Sharma wrote:
> 
> Hi Friends,
> 
> The term spilling parameter is not much clear to me, though I read in 
> forum.It would be great if anyone can help me. Also  I would like to 
> know is there any standard value for spilling paramter for Si-H system.
> 
> Thanks and regards
> 
> Dimpy (PhD)
> 
> UCC,Ireland
> 
> 
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-- 


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| Gabriele Sclauzero, PhD Student                  |
| c/o:   SISSA & CNR-INFM Democritos,              |
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| email: sclauzer at sissa.it                         |
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