Shift current - Revision history

Wikiadmin: /* Analysis of the results */

2026-03-17T13:40:10Z

Analysis of the results

← Older revision		Revision as of 15:40, 17 March 2026
Line 68:		Line 68:

	from yambopy import *		from yambopy import *
	~~from yambopy.nl.harmonic_analysis import Harmonic_Analysis~~
	from yambopy.units import fs2aut		from yambopy.units import fs2aut

Wikiadmin: /* Analysis of the results */

2026-03-06T14:31:01Z

Analysis of the results

← Older revision		Revision as of 16:31, 6 March 2026
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	from yambopy.nl.harmonic_analysis import Harmonic_Analysis		from yambopy.nl.harmonic_analysis import Harmonic_Analysis
	from yambopy.units import fs2aut		from yambopy.units import fs2aut
	~~X_order=4~~
	NLDB=YamboNLDB()		NLDB=YamboNLDB()
	SIN = Xn_from_sine(NLDB,l_out_current=True)
			SIN = Xn_from_sine(NLDB,X_order=4,l_out_current=True)
	print(SIN)		print(SIN)
	OUT = SIN.perform_analysis()		OUT = SIN.perform_analysis()

Wikiadmin: /* Analysis of the results */

2026-03-06T14:30:24Z

Analysis of the results

← Older revision		Revision as of 16:30, 6 March 2026
Line 72:		Line 72:
	X_order=4		X_order=4
	NLDB=YamboNLDB()		NLDB=YamboNLDB()
	~~Harmonic_Analysis~~(NLDB,~~X_order~~=~~X_order,prn_Peff~~=~~True~~)		SIN = Xn_from_sine(NLDB,l_out_current=True)
			print(SIN)
			OUT = SIN.perform_analysis()
			SIN.output_analysis(OUT)
			SIN.reconstruct_signal(OUT)

	This script will produce different file containing the response function of the current and polarization respect to the total field.		This script will produce different file containing the response function of the current and polarization respect to the total field.

Wikiadmin: /* Analysis of the results */

2026-01-29T14:56:18Z

Analysis of the results

@@ Line 76: / Line 76: @@
 This script will produce different file containing the response function of the current and polarization respect to the total field.
 From the second order response of the current at zero frequency, file <code>o.YamboPy-Sigma_probe_order_0</code>  we can extract the shift current coefficient along the 'y' direction
-that correspond to the 5th column of the file. <br>
+that correspond to the 5th column of the file. In the file <code>o.YamboPy-Sigma_probe_order_0:</code>
 Hereafter we report the shift current spectrum compared with the results of Ibañez-Azpiroz et al. <ref name="Azpiroz"></ref>.

Wikiadmin: /* Real-time setup and calculations */

2025-10-20T15:53:48Z

Real-time setup and calculations

← Older revision		Revision as of 17:53, 20 October 2025
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	<span style="color:red">EvalCurrent</span> # [NL] Evaluate the current		<span style="color:red">EvalCurrent</span> # [NL] Evaluate the current
	#FrPolPerdic # [DIP] Force periodicity of polarization respect to the external field		#FrPolPerdic # [DIP] Force periodicity of polarization respect to the external field
	% Field1_Freq		Field1_Freq= 0.100000 eV # [RT Field1] Frequency
	0.100000 ~~\| 0.100000 \|~~ eV ~~# [RT Field1] Frequency~~
	%
	~~Field1_NFreqs= 1~~ # [RT Field1] Frequency
	Field1_Int= 1000.00 kWLm2 # [RT Field1] Intensity		Field1_Int= 1000.00 kWLm2 # [RT Field1] Intensity
	Field1_Width= 0.000000 fs # [RT Field1] Width		Field1_Width= 0.000000 fs # [RT Field1] Width

Wikiadmin: /* References */

2025-10-17T07:21:17Z

References

← Older revision		Revision as of 09:21, 17 October 2025
Line 4:		Line 4:
	We suppose you are already familiar with the non-linear response using the Yambo code.		We suppose you are already familiar with the non-linear response using the Yambo code.
	If it is not the case please study the previous tutorials: <br>[[Linear response using Dynamical Berry Phase]] and [[Real time approach to non-linear response (SHG)]].<br>		If it is not the case please study the previous tutorials: <br>[[Linear response using Dynamical Berry Phase]] and [[Real time approach to non-linear response (SHG)]].<br>
	This theoretical implementation of this tutorial is described in the paper <ref name="yuncheng"></ref> , please cite it if you use it.<br>		This theoretical implementation of this tutorial is described in the paper <ref name="yuncheng"></ref> , please cite it if you use it. <br>
	The tutorial was created with the help of [https://www.linkedin.com/in/yuncheng-mao-8aba6279/ Yuncheng Mao].		The tutorial was created with the help of [https://www.linkedin.com/in/yuncheng-mao-8aba6279/ Yuncheng Mao].

Wikiadmin: Created page with " Shift_current == Introduction == In this tutorial we will show how to calculate Shift Current in bulk materials.
We suppose you are already familiar with the non-linear response using the Yambo code. If it is not the case please study the previous tutorials:
Linear response using Dynamical Berry Phase and Real time approach to non-linear response (SHG).
This theoretical implementation of this tutorial is descri..."

2025-10-17T07:01:05Z

Created page with "right|200px | Shift_current == Introduction == In this tutorial we will show how to calculate Shift Current in bulk materials. We suppose you are already familiar with the non-linear response using the Yambo code. If it is not the case please study the previous tutorials: Linear response using Dynamical Berry Phase and Real time approach to non-linear response (SHG). This theoretical implementation of this tutorial is descri..."

New page

[[File:Shift current.png|right|200px | Shift_current]]
== Introduction ==
In this tutorial we will show how to calculate Shift Current in bulk materials. 
We suppose you are already familiar with the non-linear response using the Yambo code.
If it is not the case please study the previous tutorials: [[Linear response using Dynamical Berry Phase]] and [[Real time approach to non-linear response (SHG)]]. 
This theoretical implementation of this tutorial is described in the paper <ref name="yuncheng"></ref> , please cite it if you use it. 
The tutorial was created with the help of [https://www.linkedin.com/in/yuncheng-mao-8aba6279/ Yuncheng Mao].

== Setup calculations ==

In this tutorial we will take as example the two dimensional GeS monolayer. 
DFT inputs can be downloaded here: [http://www.attaccalite.com/tutorials_yambo/GeS_DFT.tgz GeS_DFT.tgz]. 

First of all run the setup, then remove symmetries along the '''y''' direction, as explained in the tutorial above.

== Real-time setup and calculations ==

In order to generate input file for shift current you do: yambo_nl -u n -V par -F input.in 

nloptics # [R] Non-linear spectroscopy
NLogCPUs=0 # [PARALLEL] Live-timing CPU`s (0 for all)
PAR_def_mode= "balanced" # [PARALLEL] Default distribution mode ("balanced"/"memory"/"workload"/"KQmemory")
NL_CPU= "8 1" # [PARALLEL] CPUs for each role
NL_ROLEs= "w k" # [PARALLEL] CPUs roles (w,k)
DIP_CPU= "" # [PARALLEL] CPUs for each role
DIP_ROLEs= "" # [PARALLEL] CPUs roles (k,c,v)
OSCLL_CPU= "" # [PARALLEL] CPUs for each role
OSCLL_ROLEs= "" # [PARALLEL] CPUs roles (k,b)
DIP_Threads=0 # [OPENMP/X] Number of threads for dipoles
NL_Threads=0 # [OPENMP/NL] Number of threads for nl-optics
OSCLL_Threads=0 # [OPENMP/X] Number of threads for Oscillators
% NLBands
17 | 24 | # [NL] Bands range
%
NLverbosity= "high" # [NL] Verbosity level (low | high)
NLtime=-1.000000 fs # [NL] Simulation Time
NLintegrator= "INVINT" # [NL] Integrator ("EULEREXP/RK2/RK4/RK2EXP/HEUN/INVINT/CRANKNIC")
NLCorrelation= "IPA" # [NL] Correlation ("IPA/HARTREE/TDDFT/LRC/LRW/JGM/SEX/LSEX/LHF")
NLLrcAlpha= 0.000000 # [NL] Long Range Correction
% NLEnRange
 1.000000 | 8.000000 | eV # [NL] Energy range (for loop on frequencies NLEnSteps/=0
%
NLEnSteps= 24 # [NL] Energy steps for the loop on frequencies
% NLrotaxis
0.000000 | 0.000000 | 0.000000 | # [NL] Rotation axis (for the loop on angles NLAngSteps/=0)
%
NLAngSteps=0 # [NL] Angular steps (if NLAngSteps/=0 field versor will be ignored)
NLDamping= 0.200000 eV # [NL] Damping (or dephasing)
RADLifeTime=-1.000000 fs # [RT] Radiative life-time (if negative RADLifeTime=Phase_LifeTime)
EvalCurrent # [NL] Evaluate the current
#FrPolPerdic # [DIP] Force periodicity of polarization respect to the external field
% Field1_Freq
0.100000 | 0.100000 | eV # [RT Field1] Frequency
%
Field1_NFreqs= 1 # [RT Field1] Frequency
Field1_Int= 1000.00 kWLm2 # [RT Field1] Intensity
Field1_Width= 0.000000 fs # [RT Field1] Width
Field1_kind= "SOFTSIN" # [RT Field1] Kind(SIN|SOFTSIN| see more on src/modules/mod_fields.F)
Field1_pol= "linear" # [RT Field1] Pol(linear|circular)
% Field1_Dir
 0.000000 | 1.000000 | 0.000000 | # [RT Field1] Versor
%
Field1_Tstart= 0.010000 fs # [RT Field1] Initial Time

Notice that in this input we turned one the evaluation of current EvalCurrent and force the parallelization on the frequencies, <code>NL_CPU= "8 1"</code>, <code> NL_ROLEs= "w k</code>", that is much more efficient than the one on k-points. 
Then you can run simulation by doing: yambo_nl -F input.in

== Analysis of the results ==

In order to analyze the result we use Yambopy: [https://wiki.yambo-code.eu/wiki/index.php?title=First_steps_in_Yambopy YamboPy], and the following script for the post-processing:

from yambopy import *
from yambopy.nl.harmonic_analysis import Harmonic_Analysis
from yambopy.units import fs2aut
X_order=4
NLDB=YamboNLDB()
Harmonic_Analysis(NLDB,X_order=X_order,prn_Peff=True)

This script will produce different file containing the response function of the current and polarization respect to the total field.
From the second order response of the current at zero frequency, file <code>o.YamboPy-Sigma_probe_order_0</code> we can extract the shift current coefficient along the 'y' direction
that correspond to the 5th column of the file. 
Hereafter we report the shift current spectrum compared with the results of Ibañez-Azpiroz et al. <ref name="Azpiroz"></ref>.

[[File:Sigma2.png|center| 800px | Shift current]]

The python script to plot the results, the data from the Ibañez-Azpiroz paper can be downloaded here: [https://www.attaccalite.com/tutorials_yambo/GeS_plot.tgz GeS_plot]. 
In this example we used very few k-points, increasing the number of k-points bring the result very close to the one of Ibañez-Azpiroz, see also Supp. Mat. of Ref. <ref name="yuncheng"></ref> . 
Notice that we rescale the shift-currect for an effective thickness of 2.65 Angstrom, you can find all the rescaling factor in the python script.

Correlation effects can be included in the SC response in the same way we do for other non-linear response functions, for more info look at the tutorial:
[https://wiki.yambo-code.eu/wiki/index.php?title=SHG_within_the_TD-aGW_level_(also_called_TD-HSEX,_TD-BSE) SHG within the TD-aGW level (also called TD-HSEX, TD-BSE)]

== References ==
<references>
<ref name="yuncheng">Yuncheng Mao, Myrta Grüning, Ju Zhou, and Claudio Attaccalite, ''Shift current in 2D Janus Transition-Metal Dichalcogenides: the role of excitons
'', [https://arxiv.org/abs/2506.16067 arXiv:2506.16067(2025)]</ref>
<ref name="Azpiroz">Julen Ibañez-Azpiroz, Stepan S. Tsirkin, and Ivo Souza, ''Ab initio calculation of the shift photocurrent by Wannier interpolation'', [https://doi.org/10.1103/PhysRevB.107.205204 Phys. Rev. B '''107''', 205204 (2023)]</ref>
</references>