Yambo Community Forum

Dear Dr. Daniele Varsano,

I am trying to get adsorption spectrum for BTO (BaTiO3) and after calculating scf and nscf (QE) and converting them to yambo format using p2y, I went to initialization part using "yambo" but it gives the following warning,
[WARNING] [X] Metallic system
Based on the related info on forum, I also tried to using occupations = 'fixed' in nscf part, but I am getting the same warning. I also tried to consider ElecTemp = 0 eV and remove ndb* files, and it didn't solve the problem. Because of this, when I am going ahead and running (yambo -X s -F 01_3D_BSE_screening.in) , there is an empty input file for screening. Could you please guide me what I am doing wrong? Thank you so much.

Dear Samira,
If you’re unable to generate an input for the screening, your k‑point grid may not be uniform. You can verify this near the end of your r_setup file. If this is indeed the problem, please adjust your k‑point sampling in the nscf calculation—for example, avoid any shift by using:

K_POINTS {automatic}
6 6 2 0 0 0

If this does not resolve the issue, please post your input file and the full output on the forum so we can help troubleshoot.

Best,

Daniele

Dear Dr. Daniele Varsano,

Thank you so much. When I used the following Kpoint (6 6 2 0 0 0) , it could gave me bse.in file but still in initializations step ( writing "yambo" before everything; I have this warning :[WARNING] [X] Metallic system ) . Should I worry about it? Thank you so much in advance for your valuable guidance. I 've also attached my in - out put files for your considerations.


scf.in:
&control
calculation='scf',
prefix='bto',
restart_mode='from_scratch'
pseudo_dir = './Pseudos'
wf_collect=.true.
nstep = 200
verbosity = 'high'
/
&system
ibrav = 0,
nat= 5,
ntyp= 3,
force_symmorphic=.true.
ecutwfc = 80,
occupations = 'fixed'
/
&electrons
electron_maxstep = 100
conv_thr = 1.0e-8
/
ATOMIC_SPECIES
Ba 137.327 Ba_std.upf
Ti 47.87 Ti_std.upf
O 15.99 O_std.upf
ATOMIC_POSITIONS {crystal}
Ba 0.50 0.50 0.50
Ti 0.00 0.00 0.00
O 0.00 0.00 0.50
O 0.50 0.00 0.50
O 0.00 0.50 0.00
K_POINTS {automatic}
6 6 2 0 0 0
CELL_PARAMETERS angstrom
4.0076816400 0.0000000000 0.0000000000
0.0000000000 4.0076816400 0.0000000000
0.0000000000 0.0000000000 4.0076816400


nscf.in
&control
calculation='nscf',
prefix='bto',
pseudo_dir = './Pseudos'
nstep = 200
verbosity = 'high'
wf_collect=.true.
/
&system
ibrav = 0,
nat= 5,
ntyp= 3,
force_symmorphic=.true.
ecutwfc = 80,nbnd = 80
occupations = 'fixed'
/
&electrons
diago_thr_init=5.0e-6,
diago_full_acc=.true.
electron_maxstep = 100,
diagonalization='david'
mixing_mode = 'plain'
mixing_beta = 0.6
conv_thr = 1.0e-8
/
ATOMIC_SPECIES
Ba 137.327 Ba_std.upf
Ti 47.87 Ti_std.upf
O 15.99 O_std.upf
ATOMIC_POSITIONS {crystal}
Ba 0.50 0.50 0.50
Ti 0.00 0.00 0.00
O 0.00 0.00 0.50
O 0.50 0.00 0.50
O 0.00 0.50 0.00
K_POINTS {automatic}
6 6 2 0 0 0
CELL_PARAMETERS angstrom
4.0076816400 0.0000000000 0.0000000000
0.0000000000 4.0076816400 0.0000000000
0.0000000000 0.0000000000 4.0076816400


bse.in:
optics # [R] Linear Response optical properties
bss # [R] BSE solver
bse # [R][BSE] Bethe Salpeter Equation.
#DegFix # Force the code to impose the energy levels to respect their degeneracy
X_Threads=0 # [OPENMP/X] Number of threads for response functions
DIP_Threads=0 # [OPENMP/X] Number of threads for dipoles
K_Threads=0 # [OPENMP/BSK] Number of threads for response functions
BSKmod= "HARTREE" # [BSE] IP/Hartree/HF/ALDA/SEX/BSfxc
BSEmod= "resonant" # [BSE] resonant/retarded/coupling
BSSmod= "d" # [BSS] (h)aydock/(d)iagonalization/(s)lepc/(i)nversion/(t)ddft`
BSENGexx= 41923 RL # [BSK] Exchange components
% BSEQptR
1 | 1 | # [BSK] Transferred momenta range
%
% BSEBands
1 | 80 | # [BSK] Bands range
%
% BEnRange
0.00000 | 10.00000 | eV # [BSS] Energy range
%
% BDmRange
0.100000 | 0.100000 | eV # [BSS] Damping range
%
BEnSteps= 100 # [BSS] Energy steps
% BLongDir
1.000000 | 0.000000 | 0.000000 | # [BSS] [cc] Electric Field versor
%
BSEprop= "abs" # [BSS] Can be any among abs/jdos/kerr/asymm/anHAll/magn/dich/photolum/esrt
BSEdips= "none" # [BSS] Can be "trace/none" or "xy/xz/yz" to define off-diagonal rotation plane
#WRbsWF # [BSS] Write to disk excitonic the WFs

Dear Samira,
looking at your r_setup your k point grid is not seen as uniform: As reported in the nscf.out: Moreover, yes, your system is seen as metallic by Yambo while it is not in QE, but looking at the KS energies it seems that this is due to the fixed occupation.

I suggest you to repeat the DFT calculation using the correct ibrav and introducing a semaring in the occupations.

Best,
Daniele

Dear Dr. Daniele Varsano,


I created an O vacancy on the BaTiO3 , but again I am getting the metallic warning, i've attached my input files for your consideration, Could you please guide me how should I solve this problem. I sincerely appreciate your time.
Although the grid is uniform, but I am getting this warning.

Thank you so much.

Dear Samira,

can you also post your nscf output.

Best,

Daniele

Dear Dr. Daniele Varsano,

For sure. Thank you so much. Could you please look at the attachment.

Dear Samira,

it seems there is something odd in your QE run.
As you can see at the end of the QE output file you have this electronic configuration: i.e. the lowest conduction band lower than the highest valence band.
This probably happens because you set occupation fixed in a system that seems to be metallic.

If you expect that the system is a semiconductor, you should check your setup (cell parameter, atomic position, total charge etc...).
Otherwise, for a metallic system, you should consider a smearing in the occupation.

Best,
Daniele

Dear, Dr. Daniele Varsano

Thank you so much for your guidance.

I modified my input files but unfortunately I am getting the same error. I know it is related to my structure at QE, that is why when converting to yambo I am getting metallic error. So sorry to bother you further, if you have time, may I ask you to guide me , how should I solve it?
I need an O vacancy of BTO structure, then to do BSE calculation.
For creating O vacancy BTO, I noticed from literatures, a good option can be a neutral structure, then I create a 2 2 2 supercell BTO, added tot-charge = 0 and nspin = 2
after relaxing the structure , I used the optimized atomic positions to do scf and nscf calculation, but when I am importing data to yambo , I got "metallic error warning "

related input and output file attached for your consideration. May I ask kindly to get some guidance , why this is happening? Thank you so much for your time and help.

scf in and out files for your consideration.