Self-consistent GW on eigenvalues only - Revision history

Attacc: /* Convergence and other issues */

2021-04-09T21:12:47Z

Convergence and other issues

← Older revision		Revision as of 21:12, 9 April 2021
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	<span style="color:#FF0000"> Yambo version </span>: the '''self-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x		<span style="color:#FF0000"> Yambo version </span>: the '''self-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x

			<!--
	<span style="color:#FF0000"> Internal and external self-consistency in Yambo</span>: In Yamo there is another way to perform self-consistent GW, the use of the internal variables [[Variables#GWoIter\|GWoIter]], [[Variables#GWoIter\|GWIter]] see section [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN#Step_5:_Eigenvalue_only_self-consistent_evGW0_and_evGW Eigenvalue only self-consistent evGW0 and evGW]. We advise not to use these variables but to make an external script as described in this tutorial, because there it not restart for the GW, and therefore an interrupted job cannot be continued. Moreover the two approaches can give slightly different results. Using the internal loop the bands not included in the GW are rigidly shifted at each iteration, while in the external way Yambo performs a fit of the GW correction and apply it to the bands not included in the GW, this fit can include also the effect of stretching and can be different for the rigid shif.		<span style="color:#FF0000"> Internal and external self-consistency in Yambo</span>: In Yamo there is another way to perform self-consistent GW, the use of the internal variables [[Variables#GWoIter\|GWoIter]], [[Variables#GWoIter\|GWIter]] see section [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN#Step_5:_Eigenvalue_only_self-consistent_evGW0_and_evGW Eigenvalue only self-consistent evGW0 and evGW]. We advise not to use these variables but to make an external script as described in this tutorial, because there it not restart for the GW, and therefore an interrupted job cannot be continued. Moreover the two approaches can give slightly different results. Using the internal loop the bands not included in the GW are rigidly shifted at each iteration, while in the external way Yambo performs a fit of the GW correction and apply it to the bands not included in the GW, this fit can include also the effect of stretching and can be different for the rigid shif.
	For large bands range the two methods give the same results.		For large bands range the two methods give the same results.
			-->

	== References ==		== References ==

Attacc at 14:11, 22 February 2021

2021-02-22T14:11:38Z

← Older revision		Revision as of 14:11, 22 February 2021
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	<code>#XfnQPdb= "E < ./G0W0/ndb.QP"</code>		<code>#XfnQPdb= "E < ./G0W0/ndb.QP"</code>

	In general increasing the self-consistency ~~levels~~ gives a larger band gap: Δ<sub>DFT</sub> < Δ<sub>GoWo</sub> < Δ<sub>GWo</sub>< Δ<sub>GW</sub>.		In general increasing the self-consistency level gives larger band gap: Δ<sub>DFT</sub> < Δ<sub>GoWo</sub> < Δ<sub>GWo</sub>< Δ<sub>GW</sub>.

	[[File:Qp hbn.png\|center\| 600px \|Self-consistent GW on eigenvalues]]		[[File:Qp hbn.png\|center\| 600px \|Self-consistent GW on eigenvalues]]

Attacc at 14:10, 22 February 2021

2021-02-22T14:10:41Z

← Older revision		Revision as of 14:10, 22 February 2021
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	If you want to perform '''self-consistency only on G''' and not on W comment the line:		If you want to perform '''self-consistency only on G''' and not on W comment the line:
	<code>#XfnQPdb= "E < ./~~GW0~~/ndb.QP"</code>		<code>#XfnQPdb= "E < ./G0W0/ndb.QP"</code>

	In general increasing the self-consistency levels gives a larger band gap: Δ<sub>DFT</sub> < Δ<sub>GoWo</sub> < Δ<sub>GWo</sub>< Δ<sub>GW</sub>.		In general increasing the self-consistency levels gives a larger band gap: Δ<sub>DFT</sub> < Δ<sub>GoWo</sub> < Δ<sub>GWo</sub>< Δ<sub>GW</sub>.

Attacc: /* Convergence and other issues */

2021-02-22T10:27:45Z

Convergence and other issues

← Older revision		Revision as of 10:27, 22 February 2021
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	== Convergence and other issues ==		== Convergence and other issues ==

	<span style="color:#FF0000"> Convergence </span>: convergence parameters for the self-consistent GW are the same of the standard GoWo calculation plus the bands range [[Variables#QPkrange\|QPkrange]] employed for the self-consistency. You should perform some tests increasing the bands range and see if you converge to the same result. Notice that at each iteration the GW correction is fitted and applied also to the bands not included in the bands range. Do not use non-continuous bands/k-points range this could give wired results and the code does not check against these errors.		<span style="color:#FF0000"> Convergence </span>: convergence parameters for the self-consistent GW are the same of the [http://www.yambo-code.org/wiki/index.php?title=Silicon standard GoWo calculation] plus the bands range [[Variables#QPkrange\|QPkrange]] employed for the self-consistency. You should perform some tests increasing the bands range and see if you converge to the same result. Notice that at each iteration the GW correction is fitted and applied also to the bands not included in the bands range. Do not use non-continuous bands/k-points range this could give wired results and the code does not check against these errors.

	<span style="color:#FF0000"> Yambo version </span>: the '''self-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x		<span style="color:#FF0000"> Yambo version </span>: the '''self-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x

Attacc at 22:55, 21 February 2021

2021-02-21T22:55:55Z

← Older revision		Revision as of 22:55, 21 February 2021
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	[[File:Qp hbn.png\|center\| 600px \|Self-consistent GW on eigenvalues]]		[[File:Qp hbn.png\|center\| 600px \|Self-consistent GW on eigenvalues]]
	In this figure we show the convergence of quasi-particle energy in self-consistent GW for both G and W for hexagonal Boron Nitride, see <ref name=hbn></ref>		In this figure we show the convergence of quasi-particle energy in self-consistent GW for both G and W for hexagonal Boron Nitride, see Ref. <ref name=hbn>Artus L. et al. [https://doi.org/10.1002/adpr.202000101 Ellipsometry Study of Hexagonal Boron Nitride using Synchrotron Radiation: Transparency Window in the Far‐UVC]</ref>

	== Convergence and other issues ==		== Convergence and other issues ==

Attacc: /* Convergence and other issues */

2021-02-21T22:54:41Z

Convergence and other issues

← Older revision		Revision as of 22:54, 21 February 2021
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	== Convergence and other issues ==		== Convergence and other issues ==

	<span style="color:#FF0000"> Convergence </span>: convergence parameters for the self-consistent GW are the same of the standard GoWo calculation plus the bands range [[Variables#QPkrange\|QPkrange]] employed for the self-consistency. You should perform some tests increasing the bands range and see if you converge to the same result. Notice that at each iteration the GW correction is fitted and applied also to the bands not included in the bands range. Do not use non-continuous bands/k-points range this could give wired results and the code does not check against ~~this~~ errors.		<span style="color:#FF0000"> Convergence </span>: convergence parameters for the self-consistent GW are the same of the standard GoWo calculation plus the bands range [[Variables#QPkrange\|QPkrange]] employed for the self-consistency. You should perform some tests increasing the bands range and see if you converge to the same result. Notice that at each iteration the GW correction is fitted and applied also to the bands not included in the bands range. Do not use non-continuous bands/k-points range this could give wired results and the code does not check against these errors.

	<span style="color:#FF0000"> Yambo version </span>: the '''self-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x		<span style="color:#FF0000"> Yambo version </span>: the '''self-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x
Line 33:		Line 33:
	<span style="color:#FF0000"> Internal and external self-consistency in Yambo</span>: In Yamo there is another way to perform self-consistent GW, the use of the internal variables [[Variables#GWoIter\|GWoIter]], [[Variables#GWoIter\|GWIter]] see section [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN#Step_5:_Eigenvalue_only_self-consistent_evGW0_and_evGW Eigenvalue only self-consistent evGW0 and evGW]. We advise not to use these variables but to make an external script as described in this tutorial, because there it not restart for the GW, and therefore an interrupted job cannot be continued. Moreover the two approaches can give slightly different results. Using the internal loop the bands not included in the GW are rigidly shifted at each iteration, while in the external way Yambo performs a fit of the GW correction and apply it to the bands not included in the GW, this fit can include also the effect of stretching and can be different for the rigid shif.		<span style="color:#FF0000"> Internal and external self-consistency in Yambo</span>: In Yamo there is another way to perform self-consistent GW, the use of the internal variables [[Variables#GWoIter\|GWoIter]], [[Variables#GWoIter\|GWIter]] see section [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN#Step_5:_Eigenvalue_only_self-consistent_evGW0_and_evGW Eigenvalue only self-consistent evGW0 and evGW]. We advise not to use these variables but to make an external script as described in this tutorial, because there it not restart for the GW, and therefore an interrupted job cannot be continued. Moreover the two approaches can give slightly different results. Using the internal loop the bands not included in the GW are rigidly shifted at each iteration, while in the external way Yambo performs a fit of the GW correction and apply it to the bands not included in the GW, this fit can include also the effect of stretching and can be different for the rigid shif.
	For large bands range the two methods give the same results.		For large bands range the two methods give the same results.
	As example you can consider the results on hexgonal-Boron Nitride in ref.<ref name=hbn>Artus L. et al. [https://doi.org/10.1002/adpr.202000101 Ellipsometry Study of Hexagonal Boron Nitride using Synchrotron Radiation: Transparency Window in the Far‐UVC]</ref>

	== References ==		== References ==

Attacc at 22:41, 21 February 2021

2021-02-21T22:41:10Z

← Older revision		Revision as of 22:41, 21 February 2021
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			[[File:Evgw.png\|thumb\|Self-consistent GW]]
	In this tutorial you will learn how to perform '''self-consistent GW on eigenvalues only for G or both G and W (evGW)'''. For molecules systems and also for many solids, the G<sub>0</sub>W<sub>0</sub> approach often gives poor results.		In this tutorial you will learn how to perform '''self-consistent GW on eigenvalues only for G or both G and W (evGW)'''. For molecules systems and also for many solids, the G<sub>0</sub>W<sub>0</sub> approach often gives poor results.
	The main reason of this failure is that the DFT starting point with local or semi-local exchange correlation functionals give a too small gap compared with the experimental one, and a single shot GW is not able to correct this error.		The main reason of this failure is that the DFT starting point with local or semi-local exchange correlation functionals give a too small gap compared with the experimental one, and a single shot GW is not able to correct this error.

Attacc at 11:19, 20 February 2021

2021-02-20T11:19:23Z

← Older revision		Revision as of 11:19, 20 February 2021
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	In this tutorial we will show how to perform self-consistent GW on the eigenvalues only with the Yambo code.<br>		In this tutorial we will show how to perform self-consistent GW on the eigenvalues only with the Yambo code.<br>

	# Generate an input file for a G<sub>0</sub>W<sub>0</sub> calculation as explained in the [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN GW basics tutorial] doing: <br><code> yambo -X p -g n -p p -V qp -F yambo_g0w0_input.in </code><br>		# Generate an input file for a G<sub>0</sub>W<sub>0</sub> calculation as explained in the [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN GW basics tutorial] doing: <br><code> yambo -X p -g n -p p -V qp -F yambo_g0w0_input.in </code><br> notice that in order to perform self-consistent GW, you have to include all k-points and a reasonable number of valence and conduction bands in the [[Variables#QPkrange\|QPkrange]].
	notice that in order to perform self-consistent GW, you have to include all k-points and a reasonable number of valence and conduction bands in the [[Variables#QPkrange\|QPkrange]].
	# run your first GW calculation doing: <br><code>yambo –F yambo_g0w0_input.in -J G0W0</code>		# run your first GW calculation doing: <br><code>yambo –F yambo_g0w0_input.in -J G0W0</code>
	# at the end of the run you will get a quasi-particle file <span style="color:green">o-G0W0.qp</span>.<br> Now you can read this new quasi-particle band structure and perform another GW.<br>		# at the end of the run you will get a quasi-particle file <span style="color:green">o-G0W0.qp</span>.<br> Now you can read this new quasi-particle band structure and perform another GW.<br>

Attacc at 11:19, 20 February 2021

2021-02-20T11:19:00Z

← Older revision		Revision as of 11:19, 20 February 2021
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	In this tutorial we will show how to perform self-consistent GW on the eigenvalues only with the Yambo code.<br>		In this tutorial we will show how to perform self-consistent GW on the eigenvalues only with the Yambo code.<br>

	# Generate an input file for a G<sub>0</sub>W<sub>0</sub> calculation as explained in the [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN GW basics tutorial] doing: <br><code> yambo -X p -g n -p p -V qp -F yambo_g0w0_input.in </code>		# Generate an input file for a G<sub>0</sub>W<sub>0</sub> calculation as explained in the [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN GW basics tutorial] doing: <br><code> yambo -X p -g n -p p -V qp -F yambo_g0w0_input.in </code><br>
			notice that in order to perform self-consistent GW, you have to include all k-points and a reasonable number of valence and conduction bands in the [[Variables#QPkrange\|QPkrange]].
	# run your first GW calculation doing: <br><code>yambo –F yambo_g0w0_input.in -J G0W0</code>		# run your first GW calculation doing: <br><code>yambo –F yambo_g0w0_input.in -J G0W0</code>
	# at the end of the run you will get a quasi-particle file <span style="color:green">o-G0W0.qp</span>.<br> Now you can read this new quasi-particle band structure and perform another GW.<br>		# at the end of the run you will get a quasi-particle file <span style="color:green">o-G0W0.qp</span>.<br> Now you can read this new quasi-particle band structure and perform another GW.<br>

Attacc: /* Convergence and other issues */

2021-02-20T07:19:51Z

Convergence and other issues

← Older revision		Revision as of 07:19, 20 February 2021
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	<span style="color:#FF0000"> Convergence </span>: convergence parameters for the self-consistent GW are the same of the standard GoWo calculation plus the bands range [[Variables#QPkrange\|QPkrange]] employed for the self-consistency. You should perform some tests increasing the bands range and see if you converge to the same result. Notice that at each iteration the GW correction is fitted and applied also to the bands not included in the bands range. Do not use non-continuous bands/k-points range this could give wired results and the code does not check against this errors.		<span style="color:#FF0000"> Convergence </span>: convergence parameters for the self-consistent GW are the same of the standard GoWo calculation plus the bands range [[Variables#QPkrange\|QPkrange]] employed for the self-consistency. You should perform some tests increasing the bands range and see if you converge to the same result. Notice that at each iteration the GW correction is fitted and applied also to the bands not included in the bands range. Do not use non-continuous bands/k-points range this could give wired results and the code does not check against this errors.

	<span style="color:#FF0000"> Yambo version </span>: the s'''~~elf~~-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x		<span style="color:#FF0000"> Yambo version </span>: the '''self-consistent GW works only in Yambo 5.x''', please do not use it in Yambo 4.x

	<span style="color:#FF0000"> Internal and external self-consistency in Yambo</span>: In Yamo there is another way to perform self-consistent GW, the use of the internal variables [[Variables#GWoIter\|GWoIter]], [[Variables#GWoIter\|GWIter]] see section [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN#Step_5:_Eigenvalue_only_self-consistent_evGW0_and_evGW Eigenvalue only self-consistent evGW0 and evGW]. We advise not to use these variables but to make an external script as described in this tutorial, because there it not restart for the GW, and therefore an interrupted job cannot be continued. Moreover the two approaches can give slightly different results. Using the internal loop the bands not included in the GW are rigidly shifted at each iteration, while in the external way Yambo performs a fit of the GW correction and apply it to the bands not included in the GW, this fit can include also the effect of stretching and can be different for the rigid shif.		<span style="color:#FF0000"> Internal and external self-consistency in Yambo</span>: In Yamo there is another way to perform self-consistent GW, the use of the internal variables [[Variables#GWoIter\|GWoIter]], [[Variables#GWoIter\|GWIter]] see section [http://www.yambo-code.org/wiki/index.php?title=How_to_obtain_the_quasi-particle_band_structure_of_a_bulk_material:_h-BN#Step_5:_Eigenvalue_only_self-consistent_evGW0_and_evGW Eigenvalue only self-consistent evGW0 and evGW]. We advise not to use these variables but to make an external script as described in this tutorial, because there it not restart for the GW, and therefore an interrupted job cannot be continued. Moreover the two approaches can give slightly different results. Using the internal loop the bands not included in the GW are rigidly shifted at each iteration, while in the external way Yambo performs a fit of the GW correction and apply it to the bands not included in the GW, this fit can include also the effect of stretching and can be different for the rigid shif.