Lkind="full"

You can find here problems arising when using old releases of Yambo (< 5.0). Issues as parallelization strategy, performance issues and other technical aspects.

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Xiaoming Wang
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Re: Lkind="full"

Post by Xiaoming Wang » Wed Jul 21, 2021 5:13 pm

Hi Daniele,
Daniele Varsano wrote: ↑Wed Jul 21, 2021 4:29 pm
I had a look to your previous report, the only problem I spotted is:

Code: Select all

[WARNING]Wrong serial number for ./SCREEN//ndb.em1s
it seems that the screening was calculated for a different QE run, but if the code did not stop most probably it is compatible.
What's this warning about? Indeed I use the screening file from another run. Same dispersion was observed with that run with no such warning.

Best,
Xiaoming
Xiaoming Wang
The University of Toledo
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Re: Lkind="full"

Post by Daniele Varsano » Wed Jul 21, 2021 5:26 pm

Dear Xiamong,

here the Q is indeed k-k' and not the q of the perturbation.
In Yambo that expression is calculated exactly as you wrote as Q it is not small and you are not in the q->0 limit.

I cannot see anything wrong in your report besides the warning on the screening that was calculated from a different set of databases.
The warning is emitted as security check, if you previous run had the very same k point grid it is harmless.

I've no clue on what is going wrong here, I will do some tests.

Best,

Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
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Re: Lkind="full"

Post by Daniele Varsano » Wed Jul 21, 2021 6:03 pm

Dear Xiaoming,
another feature I noticed is that you are using a diagonal approximation for the screened interaction.
Probably this is not the reason of the problem, but can you try to comment this variable?

Code: Select all

#WehDiag
Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
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Re: Lkind="full"

Post by Davide Sangalli » Wed Jul 21, 2021 11:09 pm

Some of the points.

a) you are right, the linear dependence can be obtained only with the Coulomb cutoff
b) Lfull result depend on Blongdir as you write, not Lbar of course
c) I think I've found an issue with time reversal. LiF has inversion symmetry and t-rev is not used, while your system has only time reversal symmetry

Try the two alternative options:
1) repeat the calculation without time-reversal
2) test the following tentative fix, with time reversal
Open file src/bse/K_exchange_collisions.F replace line 161

Code: Select all

       if (i_s>nsym/(i_time_rev+1)) call dev_conjg(BS_T_grp(i_T_grp)%DEV_VAR(O_x)(:,i_T_el))
with

Code: Select all

       if (i_s>nsym/(i_time_rev+1)) call dev_conjg(BS_T_grp(i_T_grp)%DEV_VAR(O_x)(:,i_T_el),range1=(/2,BS_n_g_exch/) )
Best,
D.
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre
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Re: Lkind="full"

Post by Daniele Varsano » Thu Jul 22, 2021 6:23 am

Right,

Lfull depends on the Blongdir for the q=0 case.
when a cut-off coulomb is used i.e. V /= 1/q^2 the G=0 term in the exchange is zero and Lfull and Lbar provide the same result for q=0.

Best,
Daniele
Dr. Daniele Varsano
S3-CNR Institute of Nanoscience and MaX Center, Italy
MaX - Materials design at the Exascale
http://www.nano.cnr.it
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Xiaoming Wang
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Re: Lkind="full"

Post by Xiaoming Wang » Thu Jul 22, 2021 2:01 pm

Thanks Davide and Daniele,

I have tried
1. comment out WehDiag
2. BSEmod= "coupling"
3. The second point of Davide about time-reversal
But none of them work. I'm now trying to repeat the calculation without time reversal (the first point of Davide). Will update you later.

Best,
Xiaoming
Xiaoming Wang
The University of Toledo
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Xiaoming Wang
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Re: Lkind="full"

Post by Xiaoming Wang » Thu Jul 22, 2021 7:25 pm

Finally, I get correct exciton dispersion both with LBAR and FULL by disabling the time reversal symmetry according to Davide's suggestion #1. Thanks Davide and Daniele for all your help.

Best,
Xiaoming
Xiaoming Wang
The University of Toledo
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Davide Sangalli
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Re: Lkind="full"

Post by Davide Sangalli » Thu Jul 22, 2021 9:54 pm

Dear Xiaoming,
thank you for reaching out.
I'm a bit puzzled by the fact that the patch did not work.

Can you attach the input files of your scf/nscf simulations.
I'll try to further explore the issue.

Best,
D.
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre
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Xiaoming Wang
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Re: Lkind="full"

Post by Xiaoming Wang » Thu Jul 22, 2021 10:40 pm

Hi Davide,

The scf input is:

Code: Select all

&CONTROL
  calculation = 'scf'
  outdir = './tmp/'
  prefix = 'smpi'
  pseudo_dir = '~/soft/pseudo/dojo/pbe/fr/'
  verbosity = 'high'
/
&SYSTEM
  ecutwfc =   80
  ibrav = 0
  nat = 188
  ntyp = 5
  occupations = 'fixed'
  force_symmorphic=.TRUE.
  noncolin=.true.
  lspinorb=.true.
  !nbnd = 600
/
&ELECTRONS
  diago_full_acc = .TRUE.,
  conv_thr =  1.0d-10
  electron_maxstep = 80
  mixing_beta =   4.0000000000d-01
/
ATOMIC_SPECIES
C      12.0107   C.upf
H      1.00794   H.upf
I      126.90447 I.upf
N      14.0067   N.upf
Pb     207.2    Pb.upf
ATOMIC_POSITIONS crystal
Pb           0.8475465178       0.2588860394       0.2487114852
Pb           0.6524534822       0.7588860394       0.7512884998
Pb           0.1524534822       0.2411139606       0.7487115002
Pb           0.3475465178       0.7411139606       0.2512884998
I            0.6686973455       0.5712988105       0.2509738439
I            0.8313026545       0.0712988105       0.7490261861
I            0.3313026545       0.9287011895       0.7509738139
I            0.1686973455       0.4287011895       0.2490261561
I            0.5416844104       0.0539155185       0.2499771565
I            0.9583155896       0.5539155185       0.7500228735
I            0.4583155896       0.4460844815       0.7499771265
I            0.0416844104       0.9460844815       0.2500228435
I            0.8717586865       0.2203576777       0.3608064039
I            0.6282413135       0.7203576777       0.6391935961
I            0.1282413135       0.2796423223       0.8608064039
I            0.3717586865       0.7796423223       0.1391935961
I            0.8668817359       0.2216595585       0.1370739739
I            0.6331182641       0.7216595585       0.8629260411
I            0.1331182641       0.2783404415       0.6370739589
I            0.3668817359       0.7783404415       0.3629260411
C            0.7931398904       0.2612185954       0.0004081331
C            0.7068601096       0.7612185954       0.9995918399
C            0.2068601096       0.2387814046       0.5004081631
C            0.2931398904       0.7387814046       0.4995918669
C            0.2162469836       0.2064471575       0.0024833829
C            0.2837530164       0.7064471575       0.9975165991
C            0.7837530164       0.2935528425       0.5024834009
C            0.7162469836       0.7935528425       0.4975166291
C            0.3165736261       0.1166452145       0.9780063757
C            0.1834263739       0.6166452145       0.0219936253
C            0.6834263739       0.3833547855       0.4780063757
C            0.8165736261       0.8833547855       0.5219936243
C            0.6792689963       0.3557412395       0.0155442407
C            0.8207310037       0.8557412395       0.9844557413
C            0.3207310037       0.1442587605       0.5155442587
C            0.1792689963       0.6442587605       0.4844557713
C            0.3632935513       0.1711966880       0.0734526921
C            0.1367064487       0.6711966880       0.9265472999
C            0.6367064787       0.3288033120       0.5734527001
C            0.8632935213       0.8288033120       0.4265472999
C            0.4399968415       0.0541099881       0.0011053514
C            0.0600031585       0.5541099881       0.9988946776
C            0.5600031585       0.4458900119       0.5011053224
C            0.9399968415       0.9458900119       0.4988946476
C            0.3949109714       0.2063106414       0.1242596258
C            0.1050890286       0.7063106414       0.8757403592
C            0.6050890286       0.2936893586       0.6242596408
C            0.8949109714       0.7936893586       0.3757403592
C            0.5756751764       0.3634358829       0.9373862951
C            0.9243248236       0.8634358829       0.0626137279
C            0.4243248236       0.1365641171       0.4373862651
C            0.0756751764       0.6365641171       0.5626137049
C            0.2392299933       0.2334000206       0.0499793498
C            0.2607700067       0.7334000206       0.9500206802
C            0.7607700367       0.2665999794       0.5499793198
C            0.7392299633       0.7665999794       0.4500206502
C            0.5707775236       0.4073609142       0.9840033188
C            0.9292224764       0.9073609142       0.0159966892
C            0.4292224764       0.0926390858       0.4840033188
C            0.0707775236       0.5926390858       0.5159966812
C            0.4631890134       0.0810151567       0.0485703299
C            0.0368109866       0.5810151567       0.9514296701
C            0.5368110166       0.4189848433       0.5485703299
C            0.9631889834       0.9189848433       0.4514296701
C            0.5457170755       0.1514304811       0.8545949660
C            0.9542829245       0.6514304811       0.1454050490
C            0.4542829245       0.3485695189       0.3545949660
C            0.0457170755       0.8485695189       0.6454050340
C            0.4132953930       0.3682287226       0.1342806520
C            0.0867046070       0.8682287226       0.8657193630
C            0.5867046070       0.1317712774       0.6342806370
C            0.9132953930       0.6317712774       0.3657193630
C            0.6902499782       0.2688188564       0.9217691308
C            0.8097500218       0.7688188564       0.0782308912
C            0.3097500218       0.2311811436       0.4217691018
C            0.1902499782       0.7311811436       0.5782308692
C            0.6943948786       0.2168087372       0.8716247516
C            0.8056051214       0.7168087372       0.1283752634
C            0.3056051214       0.2831912628       0.3716247516
C            0.1943948786       0.7831912628       0.6283752484
C            0.7994814173       0.2193072719       0.9535799914
C            0.7005185827       0.7193072719       0.0464200156
C            0.2005185827       0.2806927281       0.4535799914
C            0.2994814173       0.7806927281       0.5464200086
H            0.8754557589       0.2185495152       0.0254477774
H            0.6245442411       0.7185495152       0.9745522406
H            0.1245442411       0.2814504848       0.5254477594
H            0.3754557589       0.7814504848       0.4745522106
H            0.1222166001       0.2586624189       0.9841215677
H            0.3777833849       0.7586624189       0.0158784173
H            0.8777833849       0.2413375811       0.4841215677
H            0.6222166151       0.7413375811       0.5158784323
H            0.2990994990       0.0986187594       0.9406701876
H            0.2009005010       0.5986187594       0.0593298314
H            0.7009005310       0.4013812406       0.4406701576
H            0.7990994690       0.9013812406       0.5593298124
H            0.6752391104       0.3868987628       0.0523266536
H            0.8247608896       0.8868987628       0.9476733284
H            0.3247608896       0.1131012372       0.5523266716
H            0.1752391104       0.6131012372       0.4476733574
H            0.5210168103       0.9864521619       0.9821148508
H            0.9789831897       0.4864521619       0.0178851372
H            0.4789831897       0.5135478381       0.4821148508
H            0.0210168103       0.0135478381       0.5178851492
H            0.4984054365       0.1483709904       0.1354064026
H            0.0015945635       0.6483709904       0.8645935824
H            0.5015945345       0.3516290096       0.6354064176
H            0.9984054655       0.8516290096       0.3645935824
H            0.4875612906       0.4014873516       0.9133885400
H            0.0124387094       0.9014873516       0.0866114450
H            0.5124387094       0.0985126484       0.4133885400
H            0.9875612906       0.5985126484       0.5866114600
H            0.1602705128       0.3047012387       0.0686151014
H            0.3397294872       0.8047012387       0.9313849136
H            0.8397295172       0.1952987613       0.5686150864
H            0.6602704828       0.6952987613       0.4313849136
H            0.4793171430       0.4788696640       0.9957226616
H            0.0206828570       0.9788696640       0.0042773344
H            0.5206828870       0.0211303360       0.4957226616
H            0.9793171130       0.5211303360       0.5042773384
H            0.5615603633       0.0335621677       0.0662143259
H            0.9384396367       0.5335621677       0.9337856971
H            0.4384396367       0.4664378323       0.5662143029
H            0.0615603633       0.9664378323       0.4337856671
H            0.7214050842       0.3169943013       0.8053347960
H            0.7785949158       0.8169943013       0.1946652040
H            0.2785949158       0.1830056987       0.3053347960
H            0.2214050842       0.6830056987       0.6946652040
H            0.6852138445       0.4393897917       0.8476858381
H            0.8147861555       0.9393897917       0.1523141769
H            0.3147861555       0.0606102083       0.3476858381
H            0.1852138445       0.5606102083       0.6523141619
H            0.8581805847       0.3592283711       0.8437612028
H            0.6418194153       0.8592283711       0.1562388122
H            0.1418194153       0.1407716289       0.3437612028
H            0.3581805847       0.6407716289       0.6562387972
H            0.2720457927       0.0309454701       0.1528855329
H            0.2279542073       0.5309454701       0.8471144371
H            0.7279542073       0.4690545299       0.6528855629
H            0.7720457927       0.9690545299       0.3471144671
H            0.2882142756       0.1725065495       0.1896970059
H            0.2117857244       0.6725065495       0.8103029941
H            0.7117856954       0.3274934505       0.6896970059
H            0.7882143046       0.8274934505       0.3103029941
H            0.1613997905       0.1812595454       0.1459763726
H            0.3386002095       0.6812595454       0.8540236274
H            0.8386002095       0.3187404546       0.6459763726
H            0.6613997905       0.8187404546       0.3540236274
H            0.5548340624       0.1154573637       0.8180669137
H            0.9451659376       0.6154573637       0.1819330563
H            0.4451659376       0.3845426363       0.3180669437
H            0.0548340624       0.8845426363       0.6819330863
H            0.5190780232       0.0552309360       0.8758769424
H            0.9809219768       0.5552309360       0.1241230576
H            0.4809219768       0.4447690640       0.3758769424
H            0.0190780232       0.9447690640       0.6241230576
H            0.4506904794       0.2283614435       0.8573409878
H            0.0493095206       0.7283614435       0.1426589832
H            0.5493095506       0.2716385565       0.3573410168
H            0.9506904494       0.7716385565       0.6426590122
H            0.3090842331       0.4297632716       0.1266381401
H            0.1909157669       0.9297632716       0.8733618449
H            0.6909157369       0.0702367284       0.6266381551
H            0.8090842631       0.5702367284       0.3733618449
H            0.4441101247       0.3878316830       0.1709994655
H            0.0558898753       0.8878316830       0.8290005495
H            0.5558898453       0.1121683170       0.6709994505
H            0.9441101547       0.6121683170       0.3290005495
H            0.5047171824       0.4119710971       0.1122976050
H            0.9952828176       0.9119710971       0.8877023720
H            0.4952828176       0.0880289029       0.6122976280
H            0.0047171824       0.5880289029       0.3877024020
H            0.7865815119       0.1367111100       0.8673986603
H            0.7134184881       0.6367111100       0.1326013697
H            0.2134184881       0.3632888900       0.3673986303
H            0.2865815119       0.8632888900       0.6326013397
H            0.8897471464       0.1470120762       0.9414068673
H            0.6102528536       0.6470120762       0.0585931067
H            0.1102528536       0.3529879238       0.4414068973
H            0.3897471464       0.8529879238       0.5585931327
N            0.7410779150       0.3420051996       0.8400956813
N            0.7589220850       0.8420051996       0.1599043337
N            0.2589220850       0.1579948004       0.3400956813
N            0.2410779150       0.6579948004       0.6599043187
N            0.2700972318       0.1449656419       0.1550537314
N            0.2299027682       0.6449656419       0.8449462836
N            0.7299027682       0.3550343581       0.6550537164
N            0.7700972318       0.8550343581       0.3449462836
K_POINTS automatic
4 4 1 0 0 0
CELL_PARAMETERS angstrom
      8.7848061275       0.0000000000       0.0000000000
      0.0000000000       9.1711784478       0.0000000000
      0.0000000000       0.0000000000      28.5782799514
For nscf calculation, you'll need change calculation = 'nscf', uncomment "!nbnd = 600", and change k mesh to 16x16x1.

Best,
Xiaoming
Xiaoming Wang
The University of Toledo
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Davide Sangalli
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Re: Lkind="full"

Post by Davide Sangalli » Wed Sep 01, 2021 11:54 am

Dear Xiaoming,
sorry few more questions:
Xiaoming Wang wrote: ↑Thu Jul 22, 2021 7:25 pm Finally, I get correct exciton dispersion both with LBAR and FULL by disabling the time reversal symmetry according to Davide's suggestion #1. Thanks Davide and Daniele for all your help.
1 - removing the t-rev, did it change only the dispersion with Lkind="full" or also with Lkind="Lbar"?
2 - is the epsilon obtained with "Lbar" the same as the one obtained with "full"?

Best,
D.
Davide Sangalli, PhD
CNR-ISM, Division of Ultrafast Processes in Materials (FLASHit) and MaX Centre
https://sites.google.com/view/davidesangalli
http://www.max-centre.eu/
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