The ABINIT Users Mailing List ( CLOSED )

[ธนูสิทธิ์ บุรินทร์ประโคน <thanusit@kku.ac.th>]

Dear Hai-Ping

Yes, you are right.  The number of bands we can use in screening and self-energy calculations shouldn't exceed that stored in kss file.

Regards,

Thanusit

On March 19, 2009 5:05:53 PM ICT, "lan haiping" <lanhaiping@gmail.com>, "lan haiping" <lanhaiping@gmail.com> wrote:

Thanks again.

But I am still confused. Does it mean that  the number of bands in kss file is the largest possible bands we can use in screening and self-energy calculations ?


Regards,
Hai-Ping

2009/3/19 ธนูสิทธิ์ บุ <thanusit@kku.ac.th>

Dear lan haiping

Yes, the kssform affects the number of bands stored in the kss file. In the tutorial, kssform=1 is used, abinit will store the number of bands according to the value of nbandkss. However, when kssform is 3, the way the code works was explained in the forum a long while ago. Below is the extracted reply on this issue (thanks to Matteo Giantomassi):

--------------------------

When kssform is 3, the code uses the conjugate gradient to converge the states
specified by nband, not nbandkss. When the wavefunctions are converged below tolwfr,
the SCF cycle exits and  nbandkss states are written on the KSS file.

To obtain 100 bands in the KSS file you should use nband2=100 and  nbandkss2=100.
Moreover it's worth to add a buffer during the SCF run; you might try:

  nband2=105
  nbandkss2=100
  nbdbuf 5      

--------------------------

Regards,

Thanusit Burinprakhon

On March 19, 2009 3:17:28 PM ICT, "lan haiping" <lanhaiping@gmail.com>, "lan haiping" <lanhaiping@gmail.com> wrote:

Thanks, Thanusit.
It seems I need increase the number bands in KSS calculation.
But the tutorial for GW does not have this problem. In fact , the nband for KSS calculation is set to 9.  Does kssform affect
nband for proceeding calculations ? since i found the only difference between my test and tutorial was that my kssform was set to 3.

Regards,

2009/3/19 ธนูสิทธิ์ บุ <thanusit@kku.ac.th>

Dear lan haiping

I'm not sure I get your question correctly. However, it seems that you wonder why you input the nband parameter from 200, 250, ...400, but in the output the number of bands in the self-energy calculation appears to be 100. If this is the case, please check your KSS file. It should be generated at least with nbandkss = 400 for the whole range of your convergence study to be done. If you use the kssform=3 to generate the kss file, the nband and nbandkss set for the kss file generation should be the same number. That is, you may use

      nband=400

      nbandkss=400

or with the "nbdbuf" imposed your may set

     nband=410

     nbandkss=400

     ndbbuf=10
 

Hope this helps.

Regards,

Thanusit Burinprakhon

On March 19, 2009 2:01:04 PM ICT, "lan haiping" <lanhaiping@gmail.com>, "lan haiping" <lanhaiping@gmail.com> wrote:

Dear  list:
   I did a test calculation on bands convergence of GW calculation with
abinit 5.6.3. But it seems that  the "nband" tag  didnot control over the number of bands in self-energy calculation, and the value for "mband" was ok which agreed with my setting for nband.
Below is my setting for GW parts and related output , any comment or advice  is appreciated.

GW  settings:
 ndtset 5
 # GW corrections
  optdriver  4  # driver options for self energy
  getkss 2   # KSS file used
  getscr 1   # SCR file used
  nband: 200  # bands for self energy
  nband+ 50
  ecutwfn  24 Ha #
  ecutsigx  24.0 Ha
  nkptgw    1    #
  kptgw
     0.000 0.500  0.500
  bdgw  54  55

Output
SIGMA fundamental parameters:
 PLASMON POLE MODEL  1
 number of plane-waves for SigmaX                 5961
 number of plane-waves for SigmaC and W           1139
 number of plane-waves for wavefunctions          5961
 number of bands                                   100
 number of independent spin polarizations            1
 number of k-points in IBZ                          13
 number of q-points in IBZ                          13
 number of symmetry operations                       6
 number of k-points in BZ                           64
 number of q-points in BZ                           64
 number of omega for Sigma on real axis              9
 deltae [eV]                                      0.25
 number of omega for Sigma on real axis              0
 max omega for Sigma on real axis  [eV]           0.00


Regards
--
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping@gmail.com, hplan@pku.edu.cn

Dr Thanusit Burinprakhon
Physics Department, Faculty of Science
Khon Kaen university
Khon Kaen, Thailand
40002

tel 00 66 4320-2222 ext. 2248
mobile  00 66 86-8620510

--
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping@gmail.com, hplan@pku.edu.cn

Dr Thanusit Burinprakhon
Physics Department, Faculty of Science
Khon Kaen university
Khon Kaen, Thailand
40002

tel 00 66 4320-2222 ext. 2248
mobile  00 66 86-8620510

--
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping@gmail.com, hplan@pku.edu.cn