Bandgap renormalization due to electron-phonon coupling - Revision history

Mani at 13:58, 26 February 2025

2025-02-26T13:58:50Z

← Older revision		Revision as of 13:58, 26 February 2025
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	The selection of these states can be done automatically by VASP using {{TAGO\|ELPH_SELFEN_GAPS\|True}}.		The selection of these states can be done automatically by VASP using {{TAGO\|ELPH_SELFEN_GAPS\|True}}.
	{{Available\|6.5.0}}		{{Available\|6.5.0}}
	{{NB\|tip\|The phonon-induced renormalization of the fundamental gap can alternatively be calculated from a [[Electron-phonon_interactions_from_Monte-Carlo_sampling \| stochastic approach.}}		{{NB\|tip\|The phonon-induced renormalization of the fundamental gap can alternatively be calculated from a [[Electron-phonon_interactions_from_Monte-Carlo_sampling \| stochastic approach]].}}

	==Basic usage==		==Basic usage==

Mani: Add ref to stochastic approach

2025-02-26T13:58:36Z

Add ref to stochastic approach

← Older revision		Revision as of 13:58, 26 February 2025
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	The selection of these states can be done automatically by VASP using {{TAGO\|ELPH_SELFEN_GAPS\|True}}.		The selection of these states can be done automatically by VASP using {{TAGO\|ELPH_SELFEN_GAPS\|True}}.
	{{Available\|6.5.0}}		{{Available\|6.5.0}}
			{{NB\|tip\|The phonon-induced renormalization of the fundamental gap can alternatively be calculated from a [[Electron-phonon_interactions_from_Monte-Carlo_sampling \| stochastic approach.}}

	==Basic usage==		==Basic usage==

Mani: /* Related tags and articles */ Add accumulator link

2025-02-26T11:48:17Z

Related tags and articles: Add accumulator link

← Older revision		Revision as of 11:48, 26 February 2025
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	* [[Transport coefficients including electron-phonon scattering\|Transport calculations]]		* [[Transport coefficients including electron-phonon scattering\|Transport calculations]]
	* [[Electron-phonon potential from supercells]]		* [[Electron-phonon potential from supercells]]
			* [[Electron-phonon accumulators]]
	* {{FILE\|phelel_params.hdf5}}		* {{FILE\|phelel_params.hdf5}}
	* [[Electron-phonon interactions from Monte-Carlo sampling]]		* [[Electron-phonon interactions from Monte-Carlo sampling]]

	[[Category:Electron-phonon interactions]][[Category:Howto]]		[[Category:Electron-phonon interactions]][[Category:Howto]]

Mani: /* Basic usage */ Add accumulator info

2025-02-26T11:47:55Z

Basic usage: Add accumulator info

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	To get an accurate value while using the smallest possible amount of computational resources, we recommend performing a basis set and k-point sampling convergence study.		To get an accurate value while using the smallest possible amount of computational resources, we recommend performing a basis set and k-point sampling convergence study.
	This ensures that the result is precise, provides an error estimate and reveals the computationally most favorable settings.		This ensures that the result is precise, provides an error estimate and reveals the computationally most favorable settings.

			The final output of the code is reported for each combination of computational parameters using the concept of [[Electron-phonon accumulators \| electron-phonon accumulators]].

	==Basis set convergence==		==Basis set convergence==

Mani: /* K-point sampling convergence and extrapolation to infinity */

2025-02-26T11:37:52Z

K-point sampling convergence and extrapolation to infinity

← Older revision		Revision as of 11:37, 26 February 2025
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	{{NB\|warning\|Choosing {{TAG\|ELPH_SELFEN_DELTA}} too small might produce inaccurate results for numerical reasons.}}		{{NB\|warning\|Choosing {{TAG\|ELPH_SELFEN_DELTA}} too small might produce inaccurate results for numerical reasons.}}
	The usual approach is to extrapolate the result to zero broadening.		The usual approach is to extrapolate the result to zero broadening.
	{{NB\|tip\|Multiple values can be specified for {{TAG\|ELPH_SELFEN_DELTA}}. VASP then computes the self-energy for each of these broadenings and reports the results in the {{FILE\|OUTCAR}} and {{FILE\|vaspout.h5}} files. For each value of the broadening, a new electron self-energy accumulator is created with the corresponding settings and values reported in the {{FILE\|OUTCAR}} file. This should help simplify the convergence study.}}		{{NB\|tip\|Multiple values can be specified for {{TAG\|ELPH_SELFEN_DELTA}}. VASP then computes the self-energy for each of these broadenings and reports the results in the {{FILE\|OUTCAR}} and {{FILE\|vaspout.h5}} files. For each value of the broadening, a new electron [[Electron-phonon_accumulators \| self-energy accumulator]] is created with the corresponding settings and values reported in the {{FILE\|OUTCAR}} file. This should help simplify the convergence study.}}

	==Special treatment of the dipole interaction for polar materials==		==Special treatment of the dipole interaction for polar materials==

Mani: Add related tags and articles

2025-01-20T15:16:00Z

Add related tags and articles

← Older revision		Revision as of 15:16, 20 January 2025
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	{{NB\|mind\|The long-range treatment is activated by default when the phelel_params.hdf5 file contains the dielectric tensor and born effective charges.}}		{{NB\|mind\|The long-range treatment is activated by default when the phelel_params.hdf5 file contains the dielectric tensor and born effective charges.}}
	{{NB\|tip\|The value of {{TAG\|ENCUTLR}} should be the smallest possible for efficiency reasons, but large enough such that the final quantity does not depend on it. Avoid values of {{TAG\|ENCUTLR}} that are too large, otherwise, the results might become unphysical.}}		{{NB\|tip\|The value of {{TAG\|ENCUTLR}} should be the smallest possible for efficiency reasons, but large enough such that the final quantity does not depend on it. Avoid values of {{TAG\|ENCUTLR}} that are too large, otherwise, the results might become unphysical.}}

			== Related tags and articles ==
			* [[Transport coefficients including electron-phonon scattering\|Transport calculations]]
			* [[Electron-phonon potential from supercells]]
			* {{FILE\|phelel_params.hdf5}}
			* [[Electron-phonon interactions from Monte-Carlo sampling]]

	[[Category:Electron-phonon interactions]][[Category:Howto]]		[[Category:Electron-phonon interactions]][[Category:Howto]]

Mani: Add availability notice

2025-01-20T14:47:32Z

Add availability notice

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	For the particular case where we want to determine the bandgap, we can compute the self-energy only for the states that form the gap (including all the degenerate states).		For the particular case where we want to determine the bandgap, we can compute the self-energy only for the states that form the gap (including all the degenerate states).
	The selection of these states can be done automatically by VASP using {{TAGO\|ELPH_SELFEN_GAPS\|True}}.		The selection of these states can be done automatically by VASP using {{TAGO\|ELPH_SELFEN_GAPS\|True}}.
			{{Available\|6.5.0}}

	==Basic usage==		==Basic usage==

Mani: Add categories and remove elphon release banner

2024-12-18T14:16:57Z

Add categories and remove elphon release banner

← Older revision		Revision as of 14:16, 18 December 2024
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	~~{{elph release}}~~

	The band-structure renormalization within the nonadiabatic Allen Heine Cardona (AHC) theory is computed from the real part of the electron self-energy evaluated at the Kohn-Sham (KS) eigenvalue.		The band-structure renormalization within the nonadiabatic Allen Heine Cardona (AHC) theory is computed from the real part of the electron self-energy evaluated at the Kohn-Sham (KS) eigenvalue.
	This calculation is activated by default when {{TAGO\|ELPH_RUN\|True}} and {{TAGO\|ELPH_DRIVER\|EL}}.		This calculation is activated by default when {{TAGO\|ELPH_RUN\|True}} and {{TAGO\|ELPH_DRIVER\|EL}}.
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	{{NB\|mind\|The long-range treatment is activated by default when the phelel_params.hdf5 file contains the dielectric tensor and born effective charges.}}		{{NB\|mind\|The long-range treatment is activated by default when the phelel_params.hdf5 file contains the dielectric tensor and born effective charges.}}
	{{NB\|tip\|The value of {{TAG\|ENCUTLR}} should be the smallest possible for efficiency reasons, but large enough such that the final quantity does not depend on it. Avoid values of {{TAG\|ENCUTLR}} that are too large, otherwise, the results might become unphysical.}}		{{NB\|tip\|The value of {{TAG\|ENCUTLR}} should be the smallest possible for efficiency reasons, but large enough such that the final quantity does not depend on it. Avoid values of {{TAG\|ENCUTLR}} that are too large, otherwise, the results might become unphysical.}}

			[[Category:Electron-phonon interactions]][[Category:Howto]]

Miranda.henrique at 09:13, 1 October 2024

2024-10-01T09:13:34Z

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	==Basic usage==		==Basic usage==
	The first step of an electron-phonon calculation is the [[Electron-phonon_potential_from_supercells\|computation of the electron-phonon potential]], which corresponds to the derivatives of the KS potential with ionic displacement.		The first step of an electron-phonon calculation is the [[Electron-phonon_potential_from_supercells\|computation of the electron-phonon potential]], which corresponds to the derivatives of the KS potential with ionic displacement.
	This calculation produces the {{FILE\|phelel_params.hdf5}} file which is a required input for the subsequent calculation.		This calculation produces the {{FILE\|phelel_params.hdf5}} file, which is a required input for the subsequent calculation.
	The electron-phonon matrix elements are computed using the KS states obtained from a non-self-consistent-field calculation on a dense k-point mesh.		The electron-phonon matrix elements are computed using the KS states obtained from a non-self-consistent-field calculation on a dense k-point mesh.
	This k-point mesh is specified in the {{FILE\|KPOINTS_ELPH}} file, which has the same format as the regular {{FILE\|KPOINTS}} file.		This k-point mesh is specified in the {{FILE\|KPOINTS_ELPH}} file, which has the same format as the regular {{FILE\|KPOINTS}} file.
	Note that {{TAG\|NBANDS}} governs the number of bands used in the self-consistent-field calculation, while {{TAG\|~~ELPH_BANDS~~}} governs the number of bands that will be used in the electron-phonon calculation and are computed in the grid specified via {{FILE\|KPOINTS_ELPH}}.		Note that {{TAG\|NBANDS}} governs the number of bands used in the self-consistent-field calculation, while {{TAG\|ELPH_NBANDS}} governs the number of bands that will be used in the electron-phonon calculation and are computed in the grid specified via {{FILE\|KPOINTS_ELPH}}.

	The computation of the electronic bandgap renormalization can be done using the following {{TAG\|INCAR}} file:		The computation of the electronic bandgap renormalization can be done using the following {{TAG\|INCAR}} file:

Miranda.henrique at 08:48, 1 October 2024

2024-10-01T08:48:24Z

← Older revision		Revision as of 08:48, 1 October 2024
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	To activate the long-range treatment, set the following {{FILE\|INCAR}} tags:		To activate the long-range treatment, set the following {{FILE\|INCAR}} tags:

	{{TAGBL\|ENCUTLR}} = ~~150~~		{{TAGBL\|ENCUTLR}} = 50
	{{TAGBL\|ELPH_LR}} = 1		{{TAGBL\|ELPH_LR}} = 1
	{{TAGBL\|IFC_LR}} = 1		{{TAGBL\|IFC_LR}} = 1

← Older revision		Revision as of 09:13, 1 October 2024
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	==Basic usage==		==Basic usage==
	The first step of an electron-phonon calculation is the [[Electron-phonon_potential_from_supercells\|computation of the electron-phonon potential]], which corresponds to the derivatives of the KS potential with ionic displacement.		The first step of an electron-phonon calculation is the [[Electron-phonon_potential_from_supercells\|computation of the electron-phonon potential]], which corresponds to the derivatives of the KS potential with ionic displacement.
	This calculation produces the {{FILE\|phelel_params.hdf5}} file which is a required input for the subsequent calculation.		This calculation produces the {{FILE\|phelel_params.hdf5}} file, which is a required input for the subsequent calculation.
	The electron-phonon matrix elements are computed using the KS states obtained from a non-self-consistent-field calculation on a dense k-point mesh.		The electron-phonon matrix elements are computed using the KS states obtained from a non-self-consistent-field calculation on a dense k-point mesh.
	This k-point mesh is specified in the {{FILE\|KPOINTS_ELPH}} file, which has the same format as the regular {{FILE\|KPOINTS}} file.		This k-point mesh is specified in the {{FILE\|KPOINTS_ELPH}} file, which has the same format as the regular {{FILE\|KPOINTS}} file.
	Note that {{TAG\|NBANDS}} governs the number of bands used in the self-consistent-field calculation, while {{TAG\|~~ELPH_BANDS~~}} governs the number of bands that will be used in the electron-phonon calculation and are computed in the grid specified via {{FILE\|KPOINTS_ELPH}}.		Note that {{TAG\|NBANDS}} governs the number of bands used in the self-consistent-field calculation, while {{TAG\|ELPH_NBANDS}} governs the number of bands that will be used in the electron-phonon calculation and are computed in the grid specified via {{FILE\|KPOINTS_ELPH}}.

	The computation of the electronic bandgap renormalization can be done using the following {{TAG\|INCAR}} file:		The computation of the electronic bandgap renormalization can be done using the following {{TAG\|INCAR}} file:

← Older revision		Revision as of 08:48, 1 October 2024
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	To activate the long-range treatment, set the following {{FILE\|INCAR}} tags:		To activate the long-range treatment, set the following {{FILE\|INCAR}} tags:

	{{TAGBL\|ENCUTLR}} = ~~150~~		{{TAGBL\|ENCUTLR}} = 50
	{{TAGBL\|ELPH_LR}} = 1		{{TAGBL\|ELPH_LR}} = 1
	{{TAGBL\|IFC_LR}} = 1		{{TAGBL\|IFC_LR}} = 1