Yambo Community Forum

Dear All,
I did calculation for unit cell of (3,3) carbon nanotube (CNT) and a supper cell of (3,3) CNT with 36 carbon atoms. The pw input and the yambo input are pasted below. The output of yambo is different for thess two inputs. ALso they are diferent from the repoted result in fig. 2 in PHYSICAL REVIEW B 78, 235428 2008.
Would you please let we know what is the problem?
Regards
ELAHAM
IASBS
INPUTS FOR (3,3) CNT -UNIT CELL
SCF
&control
calculation='scf'
pseudo_dir = '/home/elham/yambo/pseudo',
outdir='/home/elham/yambo/tmp',
prefix='70unitcellCNT33',
wf_collect = .true.
/
&system
ibrav= 4,
celldm(1) =28.345889829,
celldm(3) =0.1642854533333333333,
nat= 12,
ntyp= 1,
ecutwfc =70.0,
ecutrho =700.0,
occupations='smearing',
smearing='gaussian',
degauss=0.01,
force_symmorphic=.true.
/
&electrons
conv_thr = 1.D-8,
mixing_beta = 0.7
/
ATOMIC_SPECIES
C 12.0107 06-C.GGA.fhi.UPF
ATOMIC_POSITIONS (angstrom)
C 5.859851113 6.499087516 0.616067929
C 5.362619771 7.855674897 0.616070828
C 4.801550898 8.324324118 1.848214071
C 3.378096017 8.572002479 1.848211172
C 2.691699055 8.320427242 0.616067929
C 1.765475516 7.211518222 0.616070828
C 1.640148427 6.491293764 1.848214071
C 2.137379769 5.134705383 1.848211172
C 2.698448642 4.666057162 0.616067929
C 4.121903523 4.418377801 0.616070828
C 4.808300485 4.669954038 1.848214071
C 5.734524024 5.778862058 1.848211172
K_POINTS (Gamma)
NSCF

&control
calculation='nscf'
pseudo_dir = '/home/elham/espresso-4.2/pseudo',
outdir='/home/elham/CNT/data/unitcellCNT/1/tmp',
prefix='70unitcellCNT33',
restart_mode='from_scratch',
wf_collect = .true.,
/
&system
ibrav= 4,
celldm(1) =28.345889829,
celldm(3) =0.1642854533333333333,
nat= 12,
ntyp= 1,
ecutwfc =70.0,
ecutrho =700.0,
occupations='smearing',
smearing='gaussian',
degauss=0.01,
nosym =.true.,
nbnd=40 ,
force_symmorphic=.true.
/
&electrons
diago_thr_init = 1.d-5
/
&IONS
ion_dynamics ='bfgs'
/
ATOMIC_SPECIES
C 12.0107 06-C.GGA.fhi.UPF
ATOMIC_POSITIONS (angstrom)
C 5.859851113 6.499087516 0.616067929
C 5.362619771 7.855674897 0.616070828
C 4.801550898 8.324324118 1.848214071
C 3.378096017 8.572002479 1.848211172
C 2.691699055 8.320427242 0.616067929
C 1.765475516 7.211518222 0.616070828
C 1.640148427 6.491293764 1.848214071
C 2.137379769 5.134705383 1.848211172
C 2.698448642 4.666057162 0.616067929
C 4.121903523 4.418377801 0.616070828
C 4.808300485 4.669954038 1.848214071
C 5.734524024 5.778862058 1.848211172
K_POINTS {Gamma)
YAMBO
optics # [R OPT] Optics
chi # [R CHI] Dyson equation for Chi.
alda_fxc # [R TDDFT] The ALDA TDDFT kernel
% QpntsRXd
1 | 1 | # [Xd] Transferred momenta
%
% BndsRnXd
1 | 29 | # [Xd] Polarization function bands
%
NGsBlkXd= 600 RL # [Xd] Response block size
% EnRngeXd
0.00000 | 30.00000 | eV # [Xd] Energy range
%
% DmRngeXd
0.10000 | 1.10000 | eV # [Xd] Damping range
%
ETStpsXd= 200 # [Xd] Total Energy steps
% LongDrXd
1.000000 | 0.000000 | 0.000000 | # [Xd] [cc] Electric Field
%
FxcGRLc= 600 RL # [TDDFT] XC-kernel RL size
(3,3) CNT - 36 carbon atoms
SCF
&control
calculation='scf'
pseudo_dir = '/home/elham/yambo/pseudo',
outdir='/home/elham/yambo/tmp',
prefix='70CNT33'
wf_collect = .true.
/
&system
ibrav= 4,
celldm(1) =34.015067794,
celldm(3) =0.410713555,
nat= 36,
ntyp= 1,
ecutwfc =70.0,
ecutrho =700.0,
occupations='smearing',
smearing='gaussian',
degauss=0.01 ,
/
&electrons
conv_thr = 1.D-7,
mixing_beta = 0.7
/
&IONS
ion_dynamics = 'bfgs'
/
ATOMIC_SPECIES
C 12.0107 06-C.GGA.fhi.UPF
ATOMIC_POSITIONS (angstrom)
C 6.324089297 8.710084771 0.573587082
C 5.216486419 9.635233225 0.573587204
C 4.495581245 9.760676038 1.805722256
C 3.140578100 9.264036998 1.805722171
C 2.671493427 8.702432011 0.573586902
C 2.424092664 7.280643048 0.573586982
C 2.675908100 6.593598184 1.805721842
C 3.783510429 5.668450100 1.805721982
C 4.504417719 5.543012522 0.573586955
C 5.859420992 6.039652945 0.573587361
C 6.328511440 6.601254132 1.805722690
C 6.575910052 8.023042632 1.805722251
C 6.324088466 8.710084805 3.037861119
C 6.324091742 8.710087961 5.502144528
C 5.216486360 9.635231814 3.037861093
C 5.216489159 9.635235599 5.502144429
C 4.495583527 9.760672030 6.734282533
C 3.140579838 9.264033737 4.270008971
C 3.140580298 9.264031885 6.734282388
C 2.671493939 8.702431340 3.037861292
C 2.671490100 8.702431668 5.502144333
C 2.424094012 7.280643721 3.037860888
C 2.424088957 7.280642913 5.502144248
C 2.675909847 6.593600150 4.270008301
C 2.675910364 6.593602047 6.734282759
C 3.783512018 5.668452923 4.270008602
C 3.783513870 5.668454550 6.734282745
C 4.504417570 5.543013493 3.037861237
C 4.504418756 5.543008140 5.502144475
C 5.859419492 6.039653733 3.037861461
C 5.859421982 6.039649255 5.502144800
C 6.328507988 6.601255353 4.270009120
C 6.328506655 6.601255137 6.734282771
C 6.575907148 8.023043341 4.270008884
C 6.575905943 8.023044519 6.734282599
C 4.495582055 9.760673021 4.270008549
K_POINTS {Gamma}
NSCF
&control
calculation='nscf'
pseudo_dir = '/home/elham/yambo/pseudo',
outdir='/home/elham/yambo/tmp',
prefix='70CNT33',
wf_collect = .true.
restart_mode='from_scratch',
/
&system
ibrav= 4,
celldm(1) =34.015067794,
celldm(3) =0.410713555,
nat= 36,
ntyp= 1,
ecutwfc =70.0,
ecutrho =700.0,
occupations='smearing',
smearing='gaussian',
degauss=0.01 ,
nbnd = 110 ,
nosym =.true.,
force_symmorphic=.true.
/
&electrons
diago_thr_init = 1.d-5
/
&IONS
ion_dynamics = 'bfgs'
/
ATOMIC_SPECIES
C 12.0107 06-C.GGA.fhi.UPF
ATOMIC_POSITIONS (angstrom)
C 6.324089297 8.710084771 0.573587082
C 5.216486419 9.635233225 0.573587204
C 4.495581245 9.760676038 1.805722256
C 3.140578100 9.264036998 1.805722171
C 2.671493427 8.702432011 0.573586902
C 2.424092664 7.280643048 0.573586982
C 2.675908100 6.593598184 1.805721842
C 3.783510429 5.668450100 1.805721982
C 4.504417719 5.543012522 0.573586955
C 5.859420992 6.039652945 0.573587361
C 6.328511440 6.601254132 1.805722690
C 6.575910052 8.023042632 1.805722251
C 6.324088466 8.710084805 3.037861119
C 6.324091742 8.710087961 5.502144528
C 5.216486360 9.635231814 3.037861093
C 5.216489159 9.635235599 5.502144429
C 4.495583527 9.760672030 6.734282533
C 3.140579838 9.264033737 4.270008971
C 3.140580298 9.264031885 6.734282388
C 2.671493939 8.702431340 3.037861292
C 2.671490100 8.702431668 5.502144333
C 2.424094012 7.280643721 3.037860888
C 2.424088957 7.280642913 5.502144248
C 2.675909847 6.593600150 4.270008301
C 2.675910364 6.593602047 6.734282759
C 3.783512018 5.668452923 4.270008602
C 3.783513870 5.668454550 6.734282745
C 4.504417570 5.543013493 3.037861237
C 4.504418756 5.543008140 5.502144475
C 5.859419492 6.039653733 3.037861461
C 5.859421982 6.039649255 5.502144800
C 6.328507988 6.601255353 4.270009120
C 6.328506655 6.601255137 6.734282771
C 6.575907148 8.023043341 4.270008884
C 6.575905943 8.023044519 6.734282599
C 4.495582055 9.760673021 4.270008549
K_POINTS {Gamma}
optics # [R OPT] Optics
chi # [R CHI] Dyson equation for Chi.
alda_fxc # [R TDDFT] The ALDA TDDFT kernel
% QpntsRXd
1 | 1 | # [Xd] Transferred momenta
%
% BndsRnXd
1 | 111| # [Xd] Polarization function bands
%
NGsBlkXd= 600 RL # [Xd] Response block size
% EnRngeXd
0.00000 | 30.00000 | eV # [Xd] Energy range
%
% DmRngeXd
0.10000 | 1.10000 | eV # [Xd] Damping range
%
ETStpsXd= 200 # [Xd] Total Energy steps
% LongDrXd
1.000000 | 0.000000 | 0.000000 | # [Xd] [cc] Electric Field
%
FxcGRLc= 600 RL # [TDDFT] XC-kernel RL size

Dear Elham, first of all please let me remind you to fill your signature with your complete affiliation. You can do it using your user control panel.

Elham wrote: I did calculation for unit cell of (3,3) carbon nanotube (CNT) and a supper cell of (3,3) CNT with 36 carbon atoms

If I understood correctly you are trying to calculate a (3,3) tube using a cell with few atoms (how many ?) and comparing the result with a larger cell where the tube is repeated. Am I right ?

In this case one would expect, indeed, to have the same results IF the two unit cells are equivalent. Did you check the the energies of equivalent k-points are the same ? And the symmetries, are they the same ? Please compare carefully the report files of a setup run before running any optical properties calculation. Use also ypp to plot the densisites and/or wavefunctions to get more physical insight.

Regarding the PRB you should contact directly the authors of that paper because none of us participated in the calculations and we cannot provide you more details of the ones that can be read from the paper.

Andrea

Dear Andrea
I am sorry but I didn't find where fill your signature
Yes,you are right. I calculated optical property a unit cell of CNT(3,3) with 12 carbon atom and super cell of CNT(3,3) with 36 carbon atom.
this two system are different in the number of carbon atom. the other electronic property (DOS and band structure) are same.
I calculated optical property in the Gamma point because this two system in k-point aren't different. but relaxation energy are different.
With these conditions .You think which parameter I should alter that I obtained same diagram for both systems.

Best regards
Elham
IASBS

Dear Elham

You can compare the optical spectra of the two systems (the unit cell and the supercell) only when you are at convergence with the k-point mesh.
So you need to converge both calculations with respect to the k-points before you can make any comparison between the two calculations and with the literature.

For editing your signature, click on the "user control panel" link on top left of the page, then choose the profile tab and click "edit signature" in the left menu.
see also:
faq.php#f2r2

cheers,
Myrta