Category:Linear response - Revision history

Csheldon at 14:05, 24 March 2026

2026-03-24T14:05:12Z

← Older revision		Revision as of 14:05, 24 March 2026
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	[[:Category:NMR\|Nuclear magnetic resonance]] is a widely used spectroscopy technique used to probe the structure and chemical composition of molecules and solids.		[[:Category:NMR\|Nuclear magnetic resonance]] is a widely used spectroscopy technique used to probe the structure and chemical composition of molecules and solids.
	VASP can compute [[LCHIMAG\|chemical shifts]] which is the ratio between the external and induced magnetic field compared to a reference compound, [[LHYPERFINE\|hyperfine tensors]] and [[~~Electric_Field_Gradient~~\|electric field gradients]].		VASP can compute [[LCHIMAG\|chemical shifts]] which is the ratio between the external and induced magnetic field compared to a reference compound, [[LHYPERFINE\|hyperfine tensors]] and [[:Category:NMR#Quadrupolar_nuclei_-_electric_field_gradient\|electric field gradients]].

	~~== How to ==~~

			== Additional resources ==
			=== How to ===
	*[[SCH calculations\|XAS from the supercell core-hole method]]		*[[SCH calculations\|XAS from the supercell core-hole method]]
	*[[Bethe-Salpeter equation for core excitations\|XAS from the Bethe-Salpeter equation]]		*[[Bethe-Salpeter equation for core excitations\|XAS from the Bethe-Salpeter equation]]

	== Tutorials ==		=== Lectures ===
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/response/~~part1/ static and frequency-dependent response calculations].		*Lecture on {{Video\|dielectric:pedro:2025\|dielectric properties from first principles}}.
	~~<!--~~*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/xas/~~part1 SCH XAS calculations].		<!--*Lecture on {{Video\|xas:alexey:2026\|X-ray absorption spectroscopy (XAS)}}-->
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/xas/~~part2 BSE XAS calculations].		*Lecture on nuclear magnetic resonance (NMR) {{Video\|paw_nmr:gilles:2025\|theory}} and {{Video\|nmr:gilles:2025\|application}}.
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/nmr/~~part1 chemical shielding calculations].		*Lecture on {{Video\|phonons:manuel:2025\|phonons}}.
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/nmr/~~part2 coupling constants and two-center correction calculations].		*Lecture on {{Video\|linear_response:henrique:2023\|linear response}}.
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/nmr/~~part3 NICS and current calculations].~~-->~~
	*Tutorial for ~~[https://vasp.at/tutorials/latest/~~phonon/ phonon calculations].		=== Tutorials ===
	*Lecture on [https://youtu.be/0BRrAY6RrgU linear response].		*Tutorial for {{Tutorial\|response:part1\|static and frequency-dependent response calculations}}.
			*Tutorial for {{Tutorial\|xas:part1\|SCH XAS calculations}}.
			*Tutorial for {{Tutorial\|xas:part2\|BSE XAS calculations}}.
			*Tutorial for {{Tutorial\|nmr:part1\|chemical shielding calculations}}.
			*Tutorial for {{Tutorial\|nmr:part2\|coupling constants and two-center correction calculations}}.
			*Tutorial for {{Tutorial\|nmr:part3\|NICS and current calculations}}.
			*Tutorial for {{Tutorial\|phonon\|phonon calculations}}.

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]

Csheldon: /* Born effective charges */

2026-01-22T13:57:45Z

Born effective charges

← Older revision		Revision as of 13:57, 22 January 2026
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	=== Born effective charges ===		=== Born effective charges ===
	There are two approaches to compute Born effective charges implemented in VASP:		There are two approaches to compute Born effective charges implemented in VASP:
	one is done by applying [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \| finite electric fields]] along the three cartesian directions and computing the forces on the atoms which are activated using {{TAG\|LCALCEPS}} or by computing the derivating of the wavefunction with respect to an electric field using density functional perturbation theory (DFPT) using {{TAG\|LEPSILON}}.		one is done by applying [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \| finite electric fields]] along the three cartesian directions and computing the forces on the atoms which are activated using {{TAG\|LCALCEPS}} or by computing the derivating of the wavefunction with respect to an electric field using [[Electric field response from density-functional-perturbation theory \| density functional perturbation theory]] (DFPT) using {{TAG\|LEPSILON}}.

	=== Piezolectric tensor ===		=== Piezolectric tensor ===
	The piezoelectric tensor can be computed by finite differences with respect to a [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \|finite electric field]] using {{TAG\|LCALCEPS}} or		The piezoelectric tensor can be computed by finite differences with respect to a [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \|finite electric field]] using {{TAG\|LCALCEPS}} or

Singraber at 08:14, 24 October 2025

2025-10-24T08:14:26Z

← Older revision		Revision as of 08:14, 24 October 2025
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	=== Piezolectric tensor ===		=== Piezolectric tensor ===
	The piezoelectric tensor can be computed by finite differences with respect to a [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \|finite electric field]] using {{TAG\|LCALCEPS}} or		The piezoelectric tensor can be computed by finite differences with respect to a [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \|finite electric field]] using {{TAG\|LCALCEPS}} or
	by using DFPT with {{TAG\|LEPSILON}} in combination with {{~~TAGO~~\|IBRION\|5,6 or 7,8}}.		by using DFPT with {{TAG\|LEPSILON}} in combination with {{TAG\|IBRION\|5,6 or 7,8}}.

	=== Elastic tensor ===		=== Elastic tensor ===
	The elastic tensor is computed using strain finite differences using {{~~TAGO~~\|IBRION\|5,6}} in combination with {{~~TAGO~~\|ISIF\|3\|op>=}}. It is not possible to compute it using {{~~TAGO~~\|IBRION\|7,8}} because the strain perturbation is not implemented in DFPT.		The elastic tensor is computed using strain finite differences using {{TAG\|IBRION\|5,6}} in combination with {{TAG\|ISIF\|3\|op>=}}. It is not possible to compute it using {{TAG\|IBRION\|7,8}} because the strain perturbation is not implemented in DFPT.

	=== Internal strain tensor ===		=== Internal strain tensor ===
	The internal strain tensor can be computed using finite differences using {{~~TAGO~~\|IBRION\|5,6}} or DFPT using {{~~TAGO~~\|IBRION\|7,8}}.		The internal strain tensor can be computed using finite differences using {{TAG\|IBRION\|5,6}} or DFPT using {{TAG\|IBRION\|7,8}}.

	== Dynamic response ==		== Dynamic response ==

	There are [[:Category:Dielectric_properties#Dynamical_response:_Green-Kubo_and_many-body_perturbation_theory\|different approaches]] and levels of theory implemented in VASP to compute the frequency-dependent dielectric tensor. The simplest of these is done using the Green-kubo formula and is activated using {{TAG\|LOPTICS}}. This however neglects local-field effects which means that it only reproduces calculations from DFPT or finite differences of a [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \|finite electric]] field when {{~~TAGO~~\|LRPA\|.TRUE.}} when the frequency is zero (static limit). To include local field effects one should use {{~~TAGO~~\|ALGO\|CHI}}. Additionally one can include electron-hole interaction when computing the dielectric function using the Bethe-Salpeter equation in the many-body perturbation theory framework using {{~~TAGO~~\|ALGO\|BSE}}.		There are [[:Category:Dielectric_properties#Dynamical_response:_Green-Kubo_and_many-body_perturbation_theory\|different approaches]] and levels of theory implemented in VASP to compute the frequency-dependent dielectric tensor. The simplest of these is done using the Green-kubo formula and is activated using {{TAG\|LOPTICS}}. This however neglects local-field effects which means that it only reproduces calculations from DFPT or finite differences of a [[Berry_phases_and_finite_electric_fields#Self-consistent_response_to_finite_electric_fields \|finite electric]] field when {{TAG\|LRPA\|.TRUE.}} when the frequency is zero (static limit). To include local field effects one should use {{TAG\|ALGO\|CHI}}. Additionally one can include electron-hole interaction when computing the dielectric function using the Bethe-Salpeter equation in the many-body perturbation theory framework using {{TAG\|ALGO\|BSE}}.

	== X-ray absorption spectroscopy (XAS) ==		== X-ray absorption spectroscopy (XAS) ==

Csheldon: /* Tutorials */

2025-09-22T11:56:57Z

Tutorials

← Older revision		Revision as of 11:56, 22 September 2025
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	*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations].		*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations].
	*Lecture on [https://youtu.be/0BRrAY6RrgU linear response].		*Lecture on [https://youtu.be/0BRrAY6RrgU linear response].
	*Lecture on the [https://youtu.be/6F_WNIh6V7I optical bandgap].

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]

Csheldon: /* Tutorials */

2025-09-22T10:32:58Z

Tutorials

← Older revision		Revision as of 10:32, 22 September 2025
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	*Tutorial for [https://vasp.at/tutorials/latest/nmr/part1 chemical shielding calculations].		*Tutorial for [https://vasp.at/tutorials/latest/nmr/part1 chemical shielding calculations].
	*Tutorial for [https://vasp.at/tutorials/latest/nmr/part2 coupling constants and two-center correction calculations].		*Tutorial for [https://vasp.at/tutorials/latest/nmr/part2 coupling constants and two-center correction calculations].
	*Tutorial for [https://vasp.at/tutorials/latest/nmr/part3 NICS and current calculations].		*Tutorial for [https://vasp.at/tutorials/latest/nmr/part3 NICS and current calculations].-->
	*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations]. ~~-->~~		*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations].
	*Lecture on [https://youtu.be/0BRrAY6RrgU linear response].		*Lecture on [https://youtu.be/0BRrAY6RrgU linear response].
			*Lecture on the [https://youtu.be/6F_WNIh6V7I optical bandgap].

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]

Csheldon: /* Tutorials */

2025-09-22T10:12:13Z

Tutorials

← Older revision		Revision as of 10:12, 22 September 2025
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	*Tutorial for [https://vasp.at/tutorials/latest/nmr/part3 NICS and current calculations].		*Tutorial for [https://vasp.at/tutorials/latest/nmr/part3 NICS and current calculations].
	*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations]. -->		*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations]. -->
	*Lecture ~~for~~ [https://youtu.be/0BRrAY6RrgU linear response].		*Lecture on [https://youtu.be/0BRrAY6RrgU linear response].

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]

Csheldon: /* Tutorials */

2025-09-22T10:11:21Z

Tutorials

← Older revision		Revision as of 10:11, 22 September 2025
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	*Tutorial for [https://vasp.at/tutorials/latest/nmr/part3 NICS and current calculations].		*Tutorial for [https://vasp.at/tutorials/latest/nmr/part3 NICS and current calculations].
	*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations]. -->		*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations]. -->
			*Lecture for [https://youtu.be/0BRrAY6RrgU linear response].

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]

Csheldon: /* Tutorials */

2025-05-28T13:09:38Z

Tutorials

← Older revision		Revision as of 13:09, 28 May 2025
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	== Tutorials ==		== Tutorials ==
	*Tutorial for [https://vasp.at/tutorials/latest/response/part1/ static and frequency-dependent response calculations].		*Tutorial for [https://vasp.at/tutorials/latest/response/part1/ static and frequency-dependent response calculations].
			<!--*Tutorial for [https://vasp.at/tutorials/latest/xas/part1 SCH XAS calculations].
			*Tutorial for [https://vasp.at/tutorials/latest/xas/part2 BSE XAS calculations].
			*Tutorial for [https://vasp.at/tutorials/latest/nmr/part1 chemical shielding calculations].
			*Tutorial for [https://vasp.at/tutorials/latest/nmr/part2 coupling constants and two-center correction calculations].
			*Tutorial for [https://vasp.at/tutorials/latest/nmr/part3 NICS and current calculations].
			*Tutorial for [https://vasp.at/tutorials/latest/phonon/ phonon calculations]. -->

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]

Csheldon at 13:05, 28 May 2025

2025-05-28T13:05:49Z

← Older revision		Revision as of 13:05, 28 May 2025
Line 53:		Line 53:
	*[[SCH calculations\|XAS from the supercell core-hole method]]		*[[SCH calculations\|XAS from the supercell core-hole method]]
	*[[Bethe-Salpeter equation for core excitations\|XAS from the Bethe-Salpeter equation]]		*[[Bethe-Salpeter equation for core excitations\|XAS from the Bethe-Salpeter equation]]

			== Tutorials ==
			*Tutorial for [https://vasp.at/tutorials/latest/response/part1/ static and frequency-dependent response calculations].

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]

Csheldon: /* X-ray absorption spectroscopy (XAS) */

2025-05-28T11:56:42Z

X-ray absorption spectroscopy (XAS)

← Older revision		Revision as of 11:56, 28 May 2025
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	== X-ray absorption spectroscopy (XAS) ==		== X-ray absorption spectroscopy (XAS) ==

	Another case of interest is the absorption of electromagnetic radiation by core electrons as measured experimentally in [[:Category:XAS\| X-ray absorption spectroscopy (XAS)]]. The absorption spectra can be found from the imaginary part of the frequency-dependent dielectric function. Two methods for calculating XAS are available in VASP: the supercell core-hole (SCH) method and the Bethe-Salpeter equation (BSE). Both methods are capable of including the excitonic effects in the spectra. In SCH these effects are included at the DFT level, while the BSE approach relies on the many-body perturbation theory. ~~Find the~~ comparison of the two approaches [[:Category:XAS\|~~here~~]].		Another case of interest is the absorption of electromagnetic radiation by core electrons as measured experimentally in [[:Category:XAS\| X-ray absorption spectroscopy (XAS)]]. The absorption spectra can be found from the imaginary part of the frequency-dependent dielectric function. Two methods for calculating XAS are available in VASP: the supercell core-hole (SCH) method and the Bethe-Salpeter equation (BSE). Both methods are capable of including the excitonic effects in the spectra. In SCH these effects are included at the DFT level, while the BSE approach relies on the many-body perturbation theory. A comparison of the two approaches is given in the [[:Category:XAS\|XAS category page]].

	== Nuclear magnetic resonance (NMR) ==		== Nuclear magnetic resonance (NMR) ==

← Older revision		Revision as of 14:05, 24 March 2026
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	[[:Category:NMR\|Nuclear magnetic resonance]] is a widely used spectroscopy technique used to probe the structure and chemical composition of molecules and solids.		[[:Category:NMR\|Nuclear magnetic resonance]] is a widely used spectroscopy technique used to probe the structure and chemical composition of molecules and solids.
	VASP can compute [[LCHIMAG\|chemical shifts]] which is the ratio between the external and induced magnetic field compared to a reference compound, [[LHYPERFINE\|hyperfine tensors]] and [[~~Electric_Field_Gradient~~\|electric field gradients]].		VASP can compute [[LCHIMAG\|chemical shifts]] which is the ratio between the external and induced magnetic field compared to a reference compound, [[LHYPERFINE\|hyperfine tensors]] and [[:Category:NMR#Quadrupolar_nuclei_-_electric_field_gradient\|electric field gradients]].

	~~== How to ==~~

			== Additional resources ==
			=== How to ===
	*[[SCH calculations\|XAS from the supercell core-hole method]]		*[[SCH calculations\|XAS from the supercell core-hole method]]
	*[[Bethe-Salpeter equation for core excitations\|XAS from the Bethe-Salpeter equation]]		*[[Bethe-Salpeter equation for core excitations\|XAS from the Bethe-Salpeter equation]]

	== Tutorials ==		=== Lectures ===
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/response/~~part1/ static and frequency-dependent response calculations].		*Lecture on {{Video\|dielectric:pedro:2025\|dielectric properties from first principles}}.
	~~<!--~~*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/xas/~~part1 SCH XAS calculations].		<!--*Lecture on {{Video\|xas:alexey:2026\|X-ray absorption spectroscopy (XAS)}}-->
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/xas/~~part2 BSE XAS calculations].		*Lecture on nuclear magnetic resonance (NMR) {{Video\|paw_nmr:gilles:2025\|theory}} and {{Video\|nmr:gilles:2025\|application}}.
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/nmr/~~part1 chemical shielding calculations].		*Lecture on {{Video\|phonons:manuel:2025\|phonons}}.
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/nmr/~~part2 coupling constants and two-center correction calculations].		*Lecture on {{Video\|linear_response:henrique:2023\|linear response}}.
	*Tutorial for ~~[https~~:~~//vasp.at/tutorials/latest/nmr/~~part3 NICS and current calculations].~~-->~~
	*Tutorial for ~~[https://vasp.at/tutorials/latest/~~phonon/ phonon calculations].		=== Tutorials ===
	*Lecture on [https://youtu.be/0BRrAY6RrgU linear response].		*Tutorial for {{Tutorial\|response:part1\|static and frequency-dependent response calculations}}.
			*Tutorial for {{Tutorial\|xas:part1\|SCH XAS calculations}}.
			*Tutorial for {{Tutorial\|xas:part2\|BSE XAS calculations}}.
			*Tutorial for {{Tutorial\|nmr:part1\|chemical shielding calculations}}.
			*Tutorial for {{Tutorial\|nmr:part2\|coupling constants and two-center correction calculations}}.
			*Tutorial for {{Tutorial\|nmr:part3\|NICS and current calculations}}.
			*Tutorial for {{Tutorial\|phonon\|phonon calculations}}.

	[[Category:VASP\|Linear response]]		[[Category:VASP\|Linear response]]