Optical properties at finite temperature - Revision history

Attacc: /* Result analysis */

2022-05-24T19:54:25Z

Result analysis

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	2.97682190 0.551215744E-4 405.000000 8.87609196		2.97682190 0.551215744E-4 405.000000 8.87609196

	Notice that in the files you will find many ~~exciton~~ with negative energy due the full-BSE ~~nature, finally consider line-width numbers with care due to the approximation described above~~.		'''Notice''' that in the files you will find many excitons with negative energy due the anti-resonant part of the full-BSE.

	== Excitonic Eliashberg Functions ==		== Excitonic Eliashberg Functions ==

Attacc at 19:59, 7 April 2022

2022-04-07T19:59:08Z

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	and finally, we will show how to analyze the data.<br>		and finally, we will show how to analyze the data.<br>

	''' <span style="color:red">WARNING</span>''': Calculations in this tutorial are performed without double-grid, please ~~remove~~ the <code>SAVE/ndb.PH_DoubleGrid</code> ~~to reproduce the spectra~~		''' <span style="color:red">WARNING</span>''': Calculations in this tutorial are performed without double-grid, please check if the file <code>SAVE/ndb.PH_DoubleGrid</code> is present in your calculations, then remove it and rerun electron-phonon coupling before proceed with optics.

	'''Notice that there are two ways to include finite temperature effects in the BSE''':		'''Notice that there are two ways to include finite temperature effects in the BSE''':

Attacc at 15:40, 7 April 2022

2022-04-07T15:40:00Z

← Older revision		Revision as of 15:40, 7 April 2022
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	The tutorial is dived into different steps first we will calculate absorption at independent particle approximation, <br>then we will include excitonic effects,		The tutorial is dived into different steps first we will calculate absorption at independent particle approximation, <br>then we will include excitonic effects,
	and finally, we will show how to analyze the data.<br>		and finally, we will show how to analyze the data.<br>

			''' <span style="color:red">WARNING</span>''': Calculations in this tutorial are performed without double-grid, please remove the <code>SAVE/ndb.PH_DoubleGrid</code> to reproduce the spectra

	'''Notice that there are two ways to include finite temperature effects in the BSE''':		'''Notice that there are two ways to include finite temperature effects in the BSE''':

Attacc: /* Bethe-Salpeter at finite temperature (inversion solver) */

2022-04-07T12:05:31Z

Bethe-Salpeter at finite temperature (inversion solver)

← Older revision		Revision as of 12:05, 7 April 2022
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	1 \| 12 \| # [Xs] Polarization function bands		1 \| 12 \| # [Xs] Polarization function bands
	%		%
	<span style="color:red">NGsBlkXs= 113 </span> RL # [Xs] Response block size		<span style="color:red">NGsBlkXs= 113 </span> RL # [Xs] Response block size
	% LongDrXs		% LongDrXs
	1.000000 \| 0.000000 \| 0.000000 \| # [Xs] [cc] Electric Field		1.000000 \| 0.000000 \| 0.000000 \| # [Xs] [cc] Electric Field

Attacc: /* Bethe-Salpeter at finite temperature (inversion solver) */

2022-04-07T12:04:56Z

Bethe-Salpeter at finite temperature (inversion solver)

← Older revision		Revision as of 12:04, 7 April 2022
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	1 \| 12 \| # [Xs] Polarization function bands		1 \| 12 \| # [Xs] Polarization function bands
	%		%
	NGsBlkXs= 113 RL # [Xs] Response block size		<span style="color:red">NGsBlkXs= 113 </span> RL # [Xs] Response block size
	% LongDrXs		% LongDrXs
	1.000000 \| 0.000000 \| 0.000000 \| # [Xs] [cc] Electric Field		1.000000 \| 0.000000 \| 0.000000 \| # [Xs] [cc] Electric Field

Pierre: /* Result analysis */

2022-04-07T11:07:03Z

Result analysis

← Older revision		Revision as of 11:07, 7 April 2022
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	Results of BSE at finite temperature can be analized in the same way of standard BSE. You can plot exciton binging energy as a function of the temperature, exciton wave-function and so, see [https://www.yambo-code.org/wiki/index.php?title=How_to_analyse_excitons Exciton Plot tutorial].		Results of BSE at finite temperature can be analized in the same way of standard BSE. You can plot exciton binging energy as a function of the temperature, exciton wave-function and so, see [https://www.yambo-code.org/wiki/index.php?title=How_to_analyse_excitons Exciton Plot tutorial].
	For example if you sort exciton with the command <code> ypp_ph -e s -J T0_BSE</code> for the case T=0K, in addition to the exciton energy now you will find its line-width in the files .		For example if you sort exciton with the command <code> ypp_ph -e s -J T0_BSE</code> for the case T=0K, in addition to the exciton energy now you will find its line-width in the files .
	<code>o.exc_qpt1_E_sorted</code> and <code>o.exc_qpt1_I_sorted</code>.		<code>o-T0_BSE.exc_qpt1_E_sorted</code> and <code>o-T0_BSE.exc_qpt1_I_sorted</code>.
	#		#
	# Maximum Residual Value = .77136E+05		# Maximum Residual Value = .77136E+05

Pierre: /* Result analysis */

2022-04-07T11:05:05Z

Result analysis

← Older revision		Revision as of 11:05, 7 April 2022
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	== Result analysis ==		== Result analysis ==
	Results of BSE at finite temperature can be analized in the same way of standard BSE. You can plot exciton binging energy as a function of the temperature, exciton wave-function and so, see [https://www.yambo-code.org/wiki/index.php?title=How_to_analyse_excitons Exciton Plot tutorial].		Results of BSE at finite temperature can be analized in the same way of standard BSE. You can plot exciton binging energy as a function of the temperature, exciton wave-function and so, see [https://www.yambo-code.org/wiki/index.php?title=How_to_analyse_excitons Exciton Plot tutorial].
	For example if you sort exciton with the command <code> ypp_ph -e s</code> for the case T=0K, in addition to the exciton energy now you will find its line-width in the files .		For example if you sort exciton with the command <code> ypp_ph -e s -J T0_BSE</code> for the case T=0K, in addition to the exciton energy now you will find its line-width in the files .
	<code>o.exc_qpt1_E_sorted</code> and <code>o.exc_qpt1_I_sorted</code>.		<code>o.exc_qpt1_E_sorted</code> and <code>o.exc_qpt1_I_sorted</code>.
	#		#
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	Notice that in the files you will find many exciton with negative energy due the full-BSE nature, finally consider line-width numbers with care due to the approximation described above.		Notice that in the files you will find many exciton with negative energy due the full-BSE nature, finally consider line-width numbers with care due to the approximation described above.



	== Excitonic Eliashberg Functions ==		== Excitonic Eliashberg Functions ==

Pierre: /* Bethe-Salpeter at finite temperature (diagonalization solver) */

2022-04-07T11:03:04Z

Bethe-Salpeter at finite temperature (diagonalization solver)

← Older revision		Revision as of 11:03, 7 April 2022
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	In this input file we asked Yambo to include finite temperature quasi-particle in the BSE with the line <code>KfnQPdb= "E W < T0/ndb.QP" </code>, notice that we also introduce an additional rigid shift of 0.5 eV to mimic the GW correction with the line <code> 0.500000 \| 1.000000 \| 1.000000 \| \# [EXTQP BSK BSS] E parameters (c/v) eV\|adim\|adim</code>. You can now run the calculation with the command <code> yambo_ph -F yambo.in_BSE -J T0</code><br>		In this input file we asked Yambo to include finite temperature quasi-particle in the BSE with the line <code>KfnQPdb= "E W < T0/ndb.QP" </code>, notice that we also introduce an additional rigid shift of 0.5 eV to mimic the GW correction with the line <code> 0.500000 \| 1.000000 \| 1.000000 \| \# [EXTQP BSK BSS] E parameters (c/v) eV\|adim\|adim</code>. You can now run the calculation with the command <code> yambo_ph -F yambo.in_BSE -J T0_BSE</code><br>
	In principle you can calculate the GW correction following the [https://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN this tutorial] and then merge the corresponding ndb.QP database with the one of the electron-phonon coupling using the command <code> ypp -qpdb m</code>.		In principle you can calculate the GW correction following the [https://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN this tutorial] and then merge the corresponding ndb.QP database with the one of the electron-phonon coupling using the command <code> ypp -qpdb m</code>.
	Notice that we changed the BSE type to "coupling" because you need the full Bethe-Salpeter to deal with complex quasi-particles.<br>		Notice that we changed the BSE type to "coupling" because you need the full Bethe-Salpeter to deal with complex quasi-particles.<br>
	Now we do the same calculation at T = 300 K. Copy the previous input file <code> cp yambo.in_BSE yambo.in_BSE_300</code>. Then modify where the code reads the QP database :		Now we do the same calculation at T = 300 K. Copy the previous input file <code> cp yambo.in_BSE yambo.in_BSE_300</code>. Then modify where the code reads the QP database :
	<span style="color:red">KfnQPdb= "E W < T300/ndb.QP" </span> # [EXTQP BSK BSS] Database action		<span style="color:red">KfnQPdb= "E W < T300/ndb.QP" </span> # [EXTQP BSK BSS] Database action
			Run the command with <code>yambo_ph -F yambo.in_BSE_300 -J T300_BSE</code><br>
			Finally, you should be able to plot the absorption spectra from the outputs in gnuplot :
			<code> plot 'o-T0_BSE.eps_q1_diago_bse' w l t '0 K', 'o-T300_BSE.eps_q1_diago_bse' w l t '300 K'</code>
	[[File:Si bse optics.png\|800px\|center \|Bethe-Salpeter at finite temperature for bulk silicom]]		[[File:Si bse optics.png\|800px\|center \|Bethe-Salpeter at finite temperature for bulk silicom]]

Pedro at 10:55, 7 April 2022

2022-04-07T10:55:02Z

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	* The first is to use a full Bethe-Salpeter equation with all the coupling terms in such a way to treat complex quasi-particles that cannot be handled in standard (Hermitian) BSE, this is explained in section [[https://www.yambo-code.org/wiki/index.php?title=Optical_properties_at_finite_temperature#Bethe-Salpeter_at_finite_temperature_.28diagonalization_solver.29 Bethe-Salpeter at finite temperature (diagonalization solver)]]. This approach has the advantage that one can obtain excitonic eigenvalues and eigenfunctions at finite temperature and not only the optical spectrum.		* The first is to use a full Bethe-Salpeter equation with all the coupling terms in such a way to treat complex quasi-particles that cannot be handled in standard (Hermitian) BSE, this is explained in section [[https://www.yambo-code.org/wiki/index.php?title=Optical_properties_at_finite_temperature#Bethe-Salpeter_at_finite_temperature_.28diagonalization_solver.29 Bethe-Salpeter at finite temperature (diagonalization solver)]]. This approach has the advantage that one can obtain excitonic eigenvalues and eigenfunctions at finite temperature and not only the optical spectrum.

	* The second method is use of a standard ~~Hermitina~~ (resonant) BSE plus the inversion solver <ref name='dbgrid'>D. Kammerlander et al. [https://arxiv.org/abs/1209.1509 Phys. Rev. B '''86''', 125203] </ref>. In this case, a Lo two-particle Green's function that contains the complex quasi-particles is used in the solver to get a finite temperature spectrum. This approach has the advantage that can be used with the double-grid but it does not give access to eigenvalues and eigenfunctions of the BSE. This approach is described in the section: [[https://www.yambo-code.org/wiki/index.php?title=Optical_properties_at_finite_temperature#Bethe-Salpeter_at_finite_temperature_.28inversion_solver.29 Bethe-Salpeter at finite temperature (inversion solver)]]		* The second method is use of a standard Hermitinan (resonant) BSE plus the inversion solver <ref name='dbgrid'>D. Kammerlander et al. [https://arxiv.org/abs/1209.1509 Phys. Rev. B '''86''', 125203] </ref>. In this case, a Lo two-particle Green's function that contains the complex quasi-particles is used in the solver to get a finite temperature spectrum. This approach has the advantage that can be used with the double-grid but it does not give access to eigenvalues and eigenfunctions of the BSE. This approach is described in the section: [[https://www.yambo-code.org/wiki/index.php?title=Optical_properties_at_finite_temperature#Bethe-Salpeter_at_finite_temperature_.28inversion_solver.29 Bethe-Salpeter at finite temperature (inversion solver)]]

Attacc: /* Bethe-Salpeter at finite temperature (inversion solver) */

2022-04-07T10:43:14Z

Bethe-Salpeter at finite temperature (inversion solver)

← Older revision		Revision as of 10:43, 7 April 2022
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	It is possible to take into account complex quasi-particles in the BSE solution by means of the inversion procedure.		It is possible to take into account complex quasi-particles in the BSE solution by means of the inversion procedure.
	The idea is to construct an Lo (Eq. 5 of Ref.<ref name='dbgrid'></re>) that includes the electron-phonon corrections including the imaginary part.		The idea is to construct an Lo (Eq. 5 of Ref.<ref name='dbgrid'></ref>) that includes the electron-phonon corrections including the imaginary part.
	In order to generate the input you can type: <code>yambo_ph -X s -o b -k sex -y i -V qp</code>		In order to generate the input you can type: <code>yambo_ph -X s -o b -k sex -y i -V qp</code>