ABINIT Discussion Forums

Posted: **Tue Jun 09, 2015 9:09 am**

I calculated the positron lifetime of Al bulk crystal with positron=-1 and ixcpositron=2 as a test of PSN scheme and I found the bad result when setting paral_kgb=1 in both serial and parallel calculations.
Although the electronic state calculation was quickly converged, the successive positronic sate calculation ended with following warnings.

--- !WARNING
message: |
the minimization is stopped for this block
src_file: Subroutine Unknown
src_line: 0

I think that this behavior is related to the fact that the wavefunction optimization algorithm with paral_kgb=1 is different from that that with paral_kgb=0.
Please let me know if there are any solutions or suggestions. Below is my input file. I used abinit-7.8.2 and al_ps.abinit.paw included in source code as PAW atomic data.

Code: Select all

paral_kgb 1

nband   16
nstep   5000
toldfe  1.0d-8
kptopt  1  
ngkpt   4 4 4
occopt  7
tsmear  5.0d-3

# positron
positron     -1
ixcpositron  2
posocc       1.0
posnstep     5000
postoldfe    1.0d-6

#Cell and atoms definition
acell 3*4.0496 angstrom
xred
0.0 0.0 0.0
0.5 0.5 0.0
0.5 0.0 0.5
0.0 0.5 0.5

rprim 1.0 0.0 0.0
      0.0 1.0 0.0
      0.0 0.0 1.0
ntypat 1
znucl 13
natom 4
typat 4*1
chkprim 0

#Grid definitions
 ecut 20.
 pawecutdg 50.
 ecutsm 0.5

#g_l(r).Y_lm(r) are not stored in memory and recomputed
 pawstgylm 0

Takayuki Tsukagoshi

Posted: **Tue Jun 23, 2015 7:53 pm**

Hello,

The electron-positron was not fully comptaible with paral_kgb=1 in the 7.8 version.
Try first to use the last 7.10 version.
Also the pawstgylm=0 keyword was buggy, if A remember correctly; I think it;'s corrected now but you should try without it.

Posted: **Fri Jun 26, 2015 9:06 am**

Dear Mark Torrent

Thanks for your reply. I tried to use abinit-7.10.4, however, the result was same.

I would like ask you two questions:

(1) Are there any versions which are compatible with the electron-positron calculation with paral_kgb=1?
In your paer,
“Electronic structure investigation of energetics and positron lifetimes of fully relaxed monovacancies with various charge states in 3C-SiC and 6H-SiC”,
Phys. Rev. B 87. 235207 (2013)
it seems that the electron-positron calculation was conducted with paral_kgb=1 because the super cell was used.

(2) Are developers improving the code in order to calculate the positron lifetime using PSN scheme with paral_kgb=1 ?

Please comment on these points.

Takayuki Tsukagoshi

Posted: **Fri Jul 10, 2015 9:45 am**

Hi,
I have corrected this problem in the dev version of Abinit (will be available in Abinit v8)...

In the meanwhile, there is an easy "patch":
if you don't need the stress tensor (it is likely), you can put "optstress 0" in your input file... and everything should run fine.

Regards,

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Calculation of positron lifetime using PSN scheme

Calculation of positron lifetime using PSN scheme

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