Real time Bethe-Salpeter Equation (TDSE) - Revision history

Attacc: /* Approach based on the Berry Phase */

2023-09-11T17:31:46Z

Approach based on the Berry Phase

← Older revision		Revision as of 17:31, 11 September 2023
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	HARRLvcs= 1000 mHa # [HA] Hartree RL components		HARRLvcs= 1000 mHa # [HA] Hartree RL components
	EXXRLvcs= 1000 mHa # [XX] Exchange RL components		EXXRLvcs= 1000 mHa # [XX] Exchange RL components

	% ExtF_Dir		% ExtF_Dir
	<span style="color:red">0.000000 \| 1.000000 \| 0.000000 \| </span> # [NL ExtF] Versor		<span style="color:red">0.000000 \| 1.000000 \| 0.000000 \| </span> # [NL ExtF] Versor

Davide: Fixed databases download link

2023-04-11T14:41:21Z

Fixed databases download link

← Older revision		Revision as of 14:41, 11 April 2023
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	This tutorial will show how to perform a real-time calculation with Yambo on hBN monolayer. We will go through different approximations for the many body self--energy (HXC potential in the yambo language) up to the HSEX approximation which captures the physics of the exciton. For approximations local in space, like "TD-HARTREE" and "TD-DFT", the HXC potential can be evaluated directly during the simulation from real space quantities. On the contrary for approximations non local in space, one first need to compute the "real time collisions".		This tutorial will show how to perform a real-time calculation with Yambo on hBN monolayer. We will go through different approximations for the many body self--energy (HXC potential in the yambo language) up to the HSEX approximation which captures the physics of the exciton. For approximations local in space, like "TD-HARTREE" and "TD-DFT", the HXC potential can be evaluated directly during the simulation from real space quantities. On the contrary for approximations non local in space, one first need to compute the "real time collisions".

	The same DFT inputs used to generate the [http://~~www~~.yambo-code.~~org~~/educational/tutorials/files/hBN-2D-RT.tar.gz hBN-2D-RT.tar.gz], are sufficient to converge the energy of the first exciton. You will need to increase the number of k-points to converge higher energy excitons.		The same DFT inputs used to generate the [http://media.yambo-code.eu/educational/tutorials/files/hBN-2D-RT.tar.gz hBN-2D-RT.tar.gz], are sufficient to converge the energy of the first exciton. You will need to increase the number of k-points to converge higher energy excitons.

	==TD Hartree and TD DFT==		==TD Hartree and TD DFT==

Claudio: /* The Real Time Collisions */

2021-01-14T08:20:21Z

The Real Time Collisions

← Older revision		Revision as of 08:20, 14 January 2021
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	Then generate the input file to calculate the collisions (see appendix of Ref. <ref name="prb88">[https://arxiv.org/abs/1109.2424 C. Attaccalite, M. Grüning, and A. Marini PRB '''84''', 245110 (2011)]</ref>) use the command :		Then generate the input file to calculate the collisions (see appendix of Ref. <ref name="prb88">[https://arxiv.org/abs/1109.2424 C. Attaccalite, M. Grüning, and A. Marini PRB '''84''', 245110 (2011)]</ref>) use the command :
	yambo_rt -b -e -v hsex -F Inputs/03_coll_hsex.in		yambo_rt -X s -e -v hsex -F Inputs/03_coll_hsex.in

	The flag -b will tell the code to calculate the dielectric constant that is required for the screened interaction.		The flag -b will tell the code to calculate the dielectric constant that is required for the screened interaction.

Davide: /* TD Hartree and TD DFT */

2020-01-30T16:12:13Z

TD Hartree and TD DFT

← Older revision		Revision as of 16:12, 30 January 2020
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	This time we will propagate for just 20 fs. It is useful to run the simulation in background and then monitor the output file		This time we will propagate for just 20 fs. It is useful to run the simulation in background and then monitor the output file

	nohup yambo_rt -F ~~../~~Inputs_rt/02_td_hartree.in -J TD-HARTREE_1000mHa -C TD-HARTREE_1000mHa &		nohup yambo_rt -F Inputs_rt/02_td_hartree.in -J TD-HARTREE_1000mHa -C TD-HARTREE_1000mHa &
	tail -f TD-HARTREE_1000mHa/o-TD-HARTREE_1000mHa.polarization		tail -f TD-HARTREE_1000mHa/o-TD-HARTREE_1000mHa.polarization

Davide: /* References */

2020-01-29T21:14:59Z

References

← Older revision		Revision as of 21:14, 29 January 2020
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	{\| style="width:100%" border="1"		{\| style="width:100%" border="1"
	\|style="width:15%; text-align:left"\|Prev: [[Real time approach to linear response\|Independent Particles ]]		\|style="width:15%; text-align:left"\|Prev: [[Real time approach to linear response\|Independent Particles ]]
	\|style="width:70%; text-align:center"\|Now: [[~~ICTP2020~~\|~~ICTP~~ Tutorials]] --> [[Linear response from real time simulations\|Linear Response]] --> [[Real time Bethe-Salpeter Equation (TDSE)]]		\|style="width:70%; text-align:center"\|Now: [[Tutorials\|Tutorials]] --> [[Linear response from real time simulations\|Linear Response]] --> [[Real time Bethe-Salpeter Equation (TDSE)]]
	\|style="width:35%; text-align:right"\|Next: If you did all steps you can go back to the previous level		\|style="width:35%; text-align:right"\|Next: If you did all steps you can go back to the previous level
	\|-		\|-
	\|}		\|}

Davide: /* Time dependent Bethe Salpeter equation */ Changed figure

2020-01-24T11:42:54Z

Time dependent Bethe Salpeter equation: Changed figure

← Older revision		Revision as of 11:42, 24 January 2020
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	nohup yambo_rt -F Inputs_rt/04_td_hsex.in -J "TD-SEX_rt,COLL_SEX" -C TD-SEX_rt		nohup yambo_rt -F Inputs_rt/04_td_hsex.in -J "TD-SEX_rt,COLL_SEX" -C TD-SEX_rt

	~~and immediately after do the post processing~~

	~~ypp_rt -F Inputs/ypp_abs.in -J TD-sex_rt -C TD-SEX_rt~~

	=== Approach based on the Berry Phase ===		=== Approach based on the Berry Phase ===
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	nohup yambo_nl -F Inputs_nl/04_td_hsex.in -J "TD-SEX_nl,COLL_SEX" -C TD-SEX_nl		nohup yambo_nl -F Inputs_nl/04_td_hsex.in -J "TD-SEX_nl,COLL_SEX" -C TD-SEX_nl

			=== Final post processing ===

	Now you can analyze the response with		Now you can analyze the response with
			ypp_rt -F Inputs_rt/ypp_abs.in -J TD-sex_rt -C TD-SEX_rt
	ypp_nl -F Inputs_nl/ypp_abs.in -J TD-SEX_nl -C TD-SEX_nl		ypp_nl -F Inputs_nl/ypp_abs.in -J TD-SEX_nl -C TD-SEX_nl
	as it was done the linear response tutorial and compare with the TD-IP run (and eventually against the standard Bethe-Salpeter):		as it was done the linear response tutorial and compare with the TD-IP run (and eventually against the standard Bethe-Salpeter):
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	gnuplot> rep "TD-IP_rt/o-TD-IP_rt.YPP-eps_along_E" u ($1+3):2 w l		gnuplot> rep "TD-IP_rt/o-TD-IP_rt.YPP-eps_along_E" u ($1+3):2 w l

			[[File:HBN HSEX absorption.png\|thumb\|900px\|center\|In plane absorption of hBN at the TD-HSEX level compared with IP absorption]]
	[[File:~~RT BSE~~.png\|~~600px~~\|center\|~~Dielectric constant~~ with ~~excitons~~]]

	Linear response results can be obtained following the [[How to obtain an optical spectrum\|BSE tutorial]].		Linear response results can be obtained following the [[How to obtain an optical spectrum\|BSE tutorial]].

Davide: /* Approach based on the Berry Phase */

2020-01-24T10:23:28Z

Approach based on the Berry Phase

← Older revision		Revision as of 10:23, 24 January 2020
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	Now you can analyze the response with		Now you can analyze the response with
	ypp_nl -F Inputs_nl/ypp_abs.in -J TD-SEX_nl -C TD-SEX_nl		ypp_nl -F Inputs_nl/ypp_abs.in -J TD-SEX_nl -C TD-SEX_nl
	as it was done the linear response tutorial and compare with the TD-IP run (and eventually against the standard Bethe-Salpeter~~, input [[tutorials/lumen.in_bse\|here]]~~):		as it was done the linear response tutorial and compare with the TD-IP run (and eventually against the standard Bethe-Salpeter):

	gnuplot> plot "TD-HSEX_rt/o-TD-HSEX_rt.YPP-eps_along_E" u 1:2 w l		gnuplot> plot "TD-HSEX_rt/o-TD-HSEX_rt.YPP-eps_along_E" u 1:2 w l

Davide: Few global changes

2020-01-24T10:10:53Z

Few global changes

← Older revision		Revision as of 10:10, 24 January 2020
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	Thus we can expect that also the absorption will be quite similar. Indeed hBN is uniform in the plane.		Thus we can expect that also the absorption will be quite similar. Indeed hBN is uniform in the plane.
	As previously you can now to a post-processing of the polarization. The input file is exactly the same		As previously you can now to a post-processing of the polarization. The input file is exactly the same
	ypp_rt -F Inputs_rt/~~01_td_ip_ypp~~.in -J TD-HARTREE_1000mHa -C TD-HARTREE_1000mHa		ypp_rt -F Inputs_rt/ypp_abs.in -J TD-HARTREE_1000mHa -C TD-HARTREE_1000mHa
	gnuplot		gnuplot
	plot "TD-IP_rt/o-TD-IP_rt.YPP-eps_along_E" u 1:2 w l		plot "TD-IP_rt/o-TD-IP_rt.YPP-eps_along_E" u 1:2 w l
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	and once it is over do the post processing		and once it is over do the post processing
	ctrl+C		ctrl+C
	ypp_rt_4.5_gpl -F Inputs_rt/~~01_td_ip_ypp~~.in -J TD-DFT_1000mHA -C TD-DFT_1000mHA		ypp_rt_4.5_gpl -F Inputs_rt/ypp_abs.in -J TD-DFT_1000mHA -C TD-DFT_1000mHA
	gnuplot		gnuplot
	gnuplot> plot "TD-HARTREE_1000mHa/o-TD-HARTREE_1000mHa.YPP-eps_along_E" u 1:2 w l		gnuplot> plot "TD-HARTREE_1000mHa/o-TD-HARTREE_1000mHa.YPP-eps_along_E" u 1:2 w l
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	Then generate the input file to calculate the collisions (see appendix of Ref. <ref name="prb88">[https://arxiv.org/abs/1109.2424 C. Attaccalite, M. Grüning, and A. Marini PRB '''84''', 245110 (2011)]</ref>) use the command :		Then generate the input file to calculate the collisions (see appendix of Ref. <ref name="prb88">[https://arxiv.org/abs/1109.2424 C. Attaccalite, M. Grüning, and A. Marini PRB '''84''', 245110 (2011)]</ref>) use the command :
	yambo_rt -b -e -v hsex -F ~~Inputs_common~~/03_coll_hsex.in		yambo_rt -b -e -v hsex -F Inputs/03_coll_hsex.in

	The flag -b will tell the code to calculate the dielectric constant that is required for the screened interaction.		The flag -b will tell the code to calculate the dielectric constant that is required for the screened interaction.
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	collisions # [R] Eval the extended Collisions		collisions # [R] Eval the extended Collisions
	% [[Variables#COLLBands\|COLLBands]]		% [[Variables#COLLBands\|COLLBands]]
	<span style="color:red">3 </span>\| <span style="color:red"> 5 </span>\| # [COLL] Bands for the collisions		<span style="color:red">4 </span>\| <span style="color:red"> 5 </span>\| # [COLL] Bands for the collisions
	%		%
	HXC_Potential= "HARTREE+SEX" # [SC] SC HXC Potential		HXC_Potential= "HARTREE+SEX" # [SC] SC HXC Potential
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	Here one has to converge the cutoff for the Hartree and the Screened Exchange. Around <code>5000 mHa</code> is a reasonable value for hBN. In this example we will use <code>1000 mHa</code> to speed up calculations. The collisions bands <code>COLLBands</code> have to be the same number of bands you want to use in the linear/nonlinear response.		Here one has to converge the cutoff for the Hartree and the Screened Exchange. Around <code>5000 mHa</code> is a reasonable value for hBN. In this example we will use <code>1000 mHa</code> to speed up calculations. The collisions bands <code>COLLBands</code> have to be the same number of bands you want to use in the linear/nonlinear response.
	The you can run		The you can run
	yambo_rt -F ~~Inputs_common~~/03_coll_hsex.in -J COLL_HSEX -C COLL_HSEX		yambo_rt -F Inputs/03_coll_hsex.in -J COLL_HSEX -C COLL_HSEX

	The calculation will take about 1 minute in serial.		The calculation will take about 1 minute in serial.
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	=== TD-HARTREE with collisions (facultative) ===		=== TD-HARTREE with collisions (facultative) ===
	Then generate the input file to calculate the collisions (see appendix of Ref. <ref name="prb88"></ref>) use the command :		Then generate the input file to calculate the collisions (see appendix of Ref. <ref name="prb88"></ref>) use the command :
	yambo_rt -e -v h -F ~~Inputs_common~~/03_coll_hartree.in		yambo_rt -e -v h -F Inputs/03_coll_hartree.in

	with a simpler input file		with a simpler input file
	collisions # [R] Eval the extended Collisions		collisions # [R] Eval the extended Collisions
	% [[Variables#COLLBands\|COLLBands]]		% [[Variables#COLLBands\|COLLBands]]
	<span style="color:red">3 </span> \| <span style="color:red"> 5 </span> \| # [COLL] Bands for the collisions		<span style="color:red">4 </span> \| <span style="color:red"> 5 </span> \| # [COLL] Bands for the collisions
	%		%
	HXC_Potential= "HARTREE" # [SC] SC HXC Potential		HXC_Potential= "HARTREE" # [SC] SC HXC Potential
	[[Variables#HARRLvcs\|HARRLvcs]]= <span style="color:red">1000 </span>mHa # [HA] Hartree RL components		[[Variables#HARRLvcs\|HARRLvcs]]= <span style="color:red">1000 </span>mHa # [HA] Hartree RL components

	yambo_rt -F ~~Inputs_common~~/03_coll_hartree.in -J COLL_HARTREE -C COLL_HARTREE		yambo_rt -F Inputs/03_coll_hartree.in -J COLL_HARTREE -C COLL_HARTREE
	yambo_rt -F Inputs_rt/02_td_hartree.in -J "TD-HARTREE_COLL,COLL_HARTREE" -C TD-HARTREE_COLL		yambo_rt -F Inputs_rt/02_td_hartree.in -J "TD-HARTREE_COLL,COLL_HARTREE" -C TD-HARTREE_COLL

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	PhLifeTime= 100.0000 fs # [RT] Dephasing Time		PhLifeTime= 100.0000 fs # [RT] Dephasing Time
	RTstep=10.000000 as # [RT] Real Time step length		RTstep=10.000000 as # [RT] Real Time step length
	NETime= 20.00000 fs # [RT] Simulation Time		NETime= 30.00000 fs # [RT] Simulation Time
	% IOtime		% IOtime
	0.01 \| 1.00 \| 0.05 \| fs # [RT] Time between to consecutive I/O (OBSERVABLEs,CARRIERs - GF - OUTPUT)		0.01 \| 1.00 \| 0.05 \| fs # [RT] Time between to consecutive I/O (OBSERVABLEs,CARRIERs - GF - OUTPUT)
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	and immediately after do the post processing		and immediately after do the post processing

	ypp_rt -F Inputs/~~01_td_ip_ypp~~.in -J TD-sex_rt -C TD-SEX_rt		ypp_rt -F Inputs/ypp_abs.in -J TD-sex_rt -C TD-SEX_rt

	=== Approach based on the Berry Phase ===		=== Approach based on the Berry Phase ===
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	NLverbosity= "low" # [NL] Verbosity level (low \| high)		NLverbosity= "low" # [NL] Verbosity level (low \| high)
	NLstep= 0.0100 fs # [NL] Real Time step length		NLstep= 0.0100 fs # [NL] Real Time step length
	NLtime= <span style="color:red">55.00000</span> fs # [NL] Simulation Time		NLtime= <span style="color:red">20.00000</span> fs # [NL] Simulation Time
	NLintegrator= "<span style="color:red">CRANKNIC</span>" # [NL] Integrator ("EULEREXP/RK2/RK4/RK2EXP/HEUN/INVINT/CRANKNIC")		NLintegrator= "<span style="color:red">CRANKNIC</span>" # [NL] Integrator ("EULEREXP/RK2/RK4/RK2EXP/HEUN/INVINT/CRANKNIC")
	NLCorrelation= "<span style="color:red">SEX</span>" # [NL] Correlation ("IPA/HARTREE/TDDFT/LRC/LRW/JGM/SEX")		NLCorrelation= "<span style="color:red">SEX</span>" # [NL] Correlation ("IPA/HARTREE/TDDFT/LRC/LRW/JGM/SEX")
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	#FrSndOrd # [NL] Force second order in Covariant Dipoles		#FrSndOrd # [NL] Force second order in Covariant Dipoles
	#EvalCurrent # [NL] Evaluate the current		#EvalCurrent # [NL] Evaluate the current
	HARRLvcs= ~~1017~~ RL # [HA] Hartree RL components		HARRLvcs= 1000 mHa # [HA] Hartree RL components
	EXXRLvcs= ~~1074~~ mHa # [XX] Exchange RL components		EXXRLvcs= 1000 mHa # [XX] Exchange RL components

	% ExtF_Dir		% ExtF_Dir
	<span style="color:red">0.000000 \| 1.000000 \| 0.000000 \| </span> # [NL ExtF] Versor		<span style="color:red">0.000000 \| 1.000000 \| 0.000000 \| </span> # [NL ExtF] Versor
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	Now you can analyze the response with		Now you can analyze the response with
	ypp_nl -F Inputs_nl/~~01_td_ip_ypp~~.in -J TD-SEX_nl -C TD-SEX_nl		ypp_nl -F Inputs_nl/ypp_abs.in -J TD-SEX_nl -C TD-SEX_nl
	as it was done the linear response tutorial and compare with the standard Bethe-Salpeter (input [[tutorials/lumen.in_bse\|here]]):		as it was done the linear response tutorial and compare with the TD-IP run (and eventually against the standard Bethe-Salpeter, input [[tutorials/lumen.in_bse\|here]]):

			gnuplot> plot "TD-HSEX_rt/o-TD-HSEX_rt.YPP-eps_along_E" u 1:2 w l
			gnuplot> rep "TD-HSEX_nl/o-TD-HSEX_nl.YPP-eps_along_E" u 1:2 w l
			gnuplot> set xrange [3:10]
			gnuplot> set yrange [0:12]
			gnuplot> rep "TD-IP_rt/o-TD-IP_rt.YPP-eps_along_E" u ($1+3):2 w l


	[[File:RT BSE.png\|600px\|center\|Dielectric constant with excitons]]		[[File:RT BSE.png\|600px\|center\|Dielectric constant with excitons]]

Davide: /* Approach based on the Berry Phase */

2020-01-23T15:52:38Z

Approach based on the Berry Phase

← Older revision		Revision as of 15:52, 23 January 2020
Line 276:		Line 276:

	Now you can analyze the response with		Now you can analyze the response with
	ypp_nl -F Inputs_nl/~~01_ypp_nl~~.in -J TD-SEX_nl -C TD-SEX_nl		ypp_nl -F Inputs_nl/01_td_ip_ypp.in -J TD-SEX_nl -C TD-SEX_nl
	as it was done the linear response tutorial and compare with the standard Bethe-Salpeter (input [[tutorials/lumen.in_bse\|here]]):		as it was done the linear response tutorial and compare with the standard Bethe-Salpeter (input [[tutorials/lumen.in_bse\|here]]):

Davide: /* Time dependent Bethe Salpeter equation */

2020-01-23T15:49:59Z

Time dependent Bethe Salpeter equation

← Older revision		Revision as of 15:49, 23 January 2020
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	and then run the code. Notice the presence of the <code>COLL_SEX</code> among the options after <code>-J</code>		and then run the code. Notice the presence of the <code>COLL_SEX</code> among the options after <code>-J</code>

	yambo_rt -F Inputs_rt/04_td_hsex.in -J "TD-~~SEX~~,COLL_SEX" -C TD-~~SEX~~		nohup yambo_rt -F Inputs_rt/04_td_hsex.in -J "TD-SEX_rt,COLL_SEX" -C TD-SEX_rt

			and immediately after do the post processing

			ypp_rt -F Inputs/01_td_ip_ypp.in -J TD-sex_rt -C TD-SEX_rt

	=== Approach based on the Berry Phase ===		=== Approach based on the Berry Phase ===
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	yambo_nl -u -V qp -F Inputs_nl/04_td-sex.in		yambo_nl -u -V qp -F Inputs_nl/04_td-sex.in

			The input file is

	nloptics # [R NL] Non-linear optics		nloptics # [R NL] Non-linear optics
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	Notice that in the calculation we decreased the number of G-vectors in the Hartree term, [[Variables#HARRLvcs\|HARRLvcs]] to speed up the calculation, in case of BN this does not change the result because local field effects are very small in h-BN along the plane.		Notice that in the calculation we decreased the number of G-vectors in the Hartree term, [[Variables#HARRLvcs\|HARRLvcs]] to speed up the calculation, in case of BN this does not change the result because local field effects are very small in h-BN along the plane.

	yambo_nl -F Inputs_nl/04_td_hsex.in -J "TD-SEX_nl,COLL_SEX" -C TD-SEX_nl		nohup yambo_nl -F Inputs_nl/04_td_hsex.in -J "TD-SEX_nl,COLL_SEX" -C TD-SEX_nl

	Now you can analyze the response with		Now you can analyze the response with