Preparing a POTCAR - Revision history

Wolloch: /* Related tags and sections */

2024-06-26T13:26:10Z

Related tags and sections

← Older revision		Revision as of 13:26, 26 June 2024
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	==Related tags and sections==		==Related tags and sections==

	[[Available potentials]], {{FILE\|POTCAR}}, [[Choosing pseudopotentials]], [[Theory:Pseudopotential basics]], [[Projector-augmented-wave formalism]]		[[Available potentials]], {{FILE\|POTCAR}}, [[Choosing pseudopotentials]], <!--[[Theory:Pseudopotential basics]],--> [[Projector-augmented-wave formalism]]

	[[Category:Pseudopotentials]][[Category:Howto]]		[[Category:Pseudopotentials]][[Category:Howto]]

Wolloch: /* Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo2Si */

2024-06-25T14:57:24Z

Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo2Si

← Older revision		Revision as of 14:57, 25 June 2024
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	==Example for preparing a {{FILE\|POTCAR}} for the Heusler alloy TiCo<sub>2</sub>Si==		==Example for preparing a {{FILE\|POTCAR}} for the Heusler alloy TiCo<sub>2</sub>Si==

	In this example, we want to prepare a {{FILE\|POTCAR}} for a PBE calculation of ferromagnetic TiCo<sub>2</sub>Si. We are interested in the ~~size of~~ the ~~magnetic moments~~.		In this example, we want to prepare a {{FILE\|POTCAR}} for a PBE calculation of ferromagnetic TiCo<sub>2</sub>Si. We are interested in the energy difference between the ferromagnetic and the nonmagnetic solutions.

	The structure is defined by the following {{FILE\|POSCAR}}:		The structure is defined by the following {{FILE\|POSCAR}}:
Line 51:		Line 51:
	0.5000000000000000 0.5000000000000000 0.5000000000000000 Ti		0.5000000000000000 0.5000000000000000 0.5000000000000000 Ti

	We will use the potpaw_PBE.64 potential set, and since we are interested in magnetic ~~properties~~, we should use potentials with additional semicore-states in the valence. The Co_pv and Ti_sv potentials seem appropriate for the transition metals. We do not expect Si to become magnetic and are not interested in unoccupied states, so the Si potential is a good choice compared to the harder, computationally more demanding Si_GW or even Si_sv_GW.		We will use the potpaw_PBE.64 potential set, and since we are interested in small energy differences caused by different magnetic solutions, we should use potentials with additional semicore-states in the valence for the 3d metals. The Co_pv and Ti_sv potentials seem appropriate for the transition metals. We do not expect Si to become magnetic and are not interested in unoccupied states, so the Si potential is a good choice compared to the harder, computationally more demanding Si_GW or even Si_sv_GW.

	On a UNIX machine, one can use the <code>cat</code> command to concatenate files together. One can redirect the output from <code>stdout</code> to a file using the <code>></code> operator. The order in the {{FILE\|POSCAR}} dictates the order in the {{FILE\|POTCAR}}:		On a UNIX machine, one can use the <code>cat</code> command to concatenate files together. One can redirect the output from <code>stdout</code> to a file using the <code>></code> operator. The order in the {{FILE\|POSCAR}} dictates the order in the {{FILE\|POTCAR}}:

Wolloch: /* Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo2Si */

2024-06-25T13:31:36Z

Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo2Si

← Older revision		Revision as of 13:31, 25 June 2024
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	On a UNIX machine, one can use the <code>cat</code> command to concatenate files together. One can redirect the output from <code>stdout</code> to a file using the <code>></code> operator. The order in the {{FILE\|POSCAR}} dictates the order in the {{FILE\|POTCAR}}:		On a UNIX machine, one can use the <code>cat</code> command to concatenate files together. One can redirect the output from <code>stdout</code> to a file using the <code>></code> operator. The order in the {{FILE\|POSCAR}} dictates the order in the {{FILE\|POTCAR}}:
	cat ~/potpaw_PBE.64/Co_pv/POTCAR ~/potpaw_PBE.64/~~Ti_sv~~/POTCAR ~/potpaw_PBE.64/Si/POTCAR > ~/scratch/TiCo2Si/POTCAR		cat ~/potpaw_PBE.64/Co_pv/POTCAR ~/potpaw_PBE.64/Si/POTCAR ~/potpaw_PBE.64/Ti_sv/POTCAR > ~/scratch/TiCo2Si/POTCAR

	==Related tags and sections==		==Related tags and sections==

Wolloch: /* Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo2Si */

2024-06-25T08:31:36Z

Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo2Si

← Older revision		Revision as of 08:31, 25 June 2024
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	TiCo2Si		TiCo2Si
	1.0		1.0
	-2.8580789844367893 -2.~~8580789844367889~~ ~~0.0000000000000000~~		0.0000000000000000 2.8580789844367893 2.8580789844367893
	-2.~~8580789844367889~~ 0.0000000000000000 -2.~~8580789844367889~~		2.8580789844367893 0.0000000000000000 2.8580789844367893
	-0.~~0000000000000005 -~~2.~~8580789844367889 -2~~.~~8580789844367889~~		2.8580789844367893 2.8580789844367893 0.0000000000000000
	Co Si Ti		Co Si Ti
	2 1 1		2 1 1
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	0.2500000000000000 0.2500000000000000 0.2500000000000000 Co		0.2500000000000000 0.2500000000000000 0.2500000000000000 Co
	0.0000000000000000 0.0000000000000000 0.0000000000000000 Si		0.0000000000000000 0.0000000000000000 0.0000000000000000 Si
	0.~~4999999999999999~~ 0.5000000000000000 0.5000000000000000 Ti		0.5000000000000000 0.5000000000000000 0.5000000000000000 Ti

	We will use the potpaw_PBE.64 potential set, and since we are interested in magnetic properties, we should use potentials with additional semicore-states in the valence. The Co_pv and Ti_sv potentials seem appropriate for the transition metals. We do not expect Si to become magnetic and are not interested in unoccupied states, so the Si potential is a good choice compared to the harder, computationally more demanding Si_GW or even Si_sv_GW.		We will use the potpaw_PBE.64 potential set, and since we are interested in magnetic properties, we should use potentials with additional semicore-states in the valence. The Co_pv and Ti_sv potentials seem appropriate for the transition metals. We do not expect Si to become magnetic and are not interested in unoccupied states, so the Si potential is a good choice compared to the harder, computationally more demanding Si_GW or even Si_sv_GW.

Huebsch: /* Step-by-step instructions */

2024-06-12T09:29:22Z

Step-by-step instructions

← Older revision		Revision as of 09:29, 12 June 2024
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	'''Step 5:''' For a single element in the structure, you can copy the {{FILE\|POTCAR}} to the working directory, e.g,		'''Step 5:''' For a single element in the structure, you can copy the {{FILE\|POTCAR}} to the working directory, e.g,
	cp ~/pot/Al/POTCAR .		cp /path/to/pot/Al/POTCAR .
	:For structures with multiple elements, the selected {{FILE\|POTCAR}} files must be concatenated to create one {{FILE\|POTCAR}} file containing all species present in the structure. Combine the potentials by entering, for instance,		:For structures with multiple elements, the selected {{FILE\|POTCAR}} files must be concatenated to create one {{FILE\|POTCAR}} file containing all species present in the structure. Combine the potentials by entering, for instance,
	cat ~/pot/Al/POTCAR ~/pot/C/POTCAR ~/pot/H/POTCAR > POTCAR		cat /path/to/pot/Al/POTCAR /path/to/pot/C/POTCAR /path/to/pot/H/POTCAR > POTCAR

	:The order of the potentials must correspond to the order of the species in the {{FILE\|POSCAR}} file.		:The order of the potentials must correspond to the order of the species in the {{FILE\|POSCAR}} file.

Huebsch: /* Step-by-step instructions */

2024-06-12T09:27:28Z

Step-by-step instructions

← Older revision		Revision as of 09:27, 12 June 2024
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	'''Step 2:''' Choose		'''Step 2:''' Choose
	* [[Available_pseudopotentials#Standard_potentials\|standard potentials]] for calculations depending mainly on occupied states, e.g., within density-functional theory, or		* [[Available_pseudopotentials#Standard_potentials\|standard potentials]] for calculations depending mainly on occupied states, e.g., within density-functional theory, using [[hybrid functionals]], or
	* [[Available_pseudopotentials#GW_potentials\|GW variants]] if the calculation requires high accuracy for unoccupied states, i.e., for [[optical properties\|optical response]] and [[many-body perturbation theory]].		* [[Available_pseudopotentials#GW_potentials\|GW variants]] if the calculation requires high accuracy for unoccupied states, i.e., for [[optical properties\|optical response]] and [[many-body perturbation theory]].

	'''Step 3:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]].		'''Step 3:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]].
	{{NB\|tip\|The standard choice is to use the [[Available_pseudopotentials#Standard_potentials\|~~GGA/~~PBE version]] based on {{TAG\|LEXCH}}{{=}}PE.\|:}}		{{NB\|tip\|The standard choice is to use the [[Available_pseudopotentials#Standard_potentials\|PBE version]] based on {{TAG\|LEXCH}}{{=}}PE which has a high transferability to other [[XC functionals]].\|:}}
	:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. ~~One~~ set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}~~. We recommend using the latest available potentials. Older versions are available to ensure reproducibility~~.		:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. In most versions, one set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}.

	'''Step 4 (optional):''' Choose a ~~{{FILE~~\|~~POTCAR}} with a~~ different atomic configuration ~~or hard version~~.		'''Step 4 (optional):''' Choose a [[Available pseudopotentials#Different variants specified by the suffix\|different variant (reference atomic valence configuration, etc.) specified by the suffix]].
	{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}		{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}
	:See [[choosing pseudopotentials]].		:See [[choosing pseudopotentials]].

Wolloch: /* Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo_2Si */

2024-06-11T14:37:32Z

Example for preparing a {{FILE|POTCAR}} for the Heusler alloy TiCo_2Si

← Older revision		Revision as of 14:37, 11 June 2024
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	{{NB\|mind\|You can mix and match {{FILE\|POTCAR}} families. Even combining pseudopotentials generated with different [[XC functionals]] is possible, however make sure to specify the [[XC functional]] in the {{FILE\|INCAR}}, see {{TAG\|XC}}.}}		{{NB\|mind\|You can mix and match {{FILE\|POTCAR}} families. Even combining pseudopotentials generated with different [[XC functionals]] is possible, however make sure to specify the [[XC functional]] in the {{FILE\|INCAR}}, see {{TAG\|XC}}.}}

	==Example for preparing a {{FILE\|POTCAR}} for the Heusler alloy TiCo<~~math~~>_2</~~math~~>Si==		==Example for preparing a {{FILE\|POTCAR}} for the Heusler alloy TiCo<sub>2</sub>Si==

	In this example, we want to prepare a {{FILE\|POTCAR}} for a PBE calculation of ferromagnetic TiCo<~~math~~>_2</~~math~~>Si. We are interested in the size of the magnetic moments.		In this example, we want to prepare a {{FILE\|POTCAR}} for a PBE calculation of ferromagnetic TiCo<sub>2</sub>Si. We are interested in the size of the magnetic moments.

	The structure is defined by the following {{FILE\|POSCAR}}:		The structure is defined by the following {{FILE\|POSCAR}}:

Huebsch at 13:52, 11 June 2024

2024-06-11T13:52:23Z

← Older revision		Revision as of 13:52, 11 June 2024
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	The {{FILE\|POTCAR}} file is a mandatory [[Input files\|input file]] that holds the [[:Category:Pseudopotentials\|pseudopotential]] for each element in the structure. The templates for each element can be downloaded from the [https://www.vasp.at/sign_in/portal/ VASP Portal]. Copy the templates to one file named {{FILE\|POTCAR}} in the working directory. It is important to paste the templates in the same order as the elements are specified in the {{FILE\|POSCAR}}, e.g., by entering		The {{FILE\|POTCAR}} file is a mandatory [[Input files\|input file]] that holds the [[:Category:Pseudopotentials\|pseudopotential]] for each element in the structure. The templates for each element can be downloaded from the [https://www.vasp.at/sign_in/portal/ VASP Portal].
			There are sometimes multiple templates for one element with subtle differences.
	~~cat ~/potpaw_PBE.64/C/POTCAR ~/potpaw_PBE.64/O_h/POTCAR > POTCAR~~

	~~As explained in detail below, there~~ are sometimes multiple templates for one element with subtle differences.
	~~{{NB\|tip\|Generally opt for the standard, computationally cheapest {{FILE\|POTCAR}} files, but test if the property of interest is sensitive to the choice of the pseudopotential.}}~~

	==Step-by-step instructions==		==Step-by-step instructions==
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	{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}		{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}
	:See [[choosing pseudopotentials]].		:See [[choosing pseudopotentials]].
			{{NB\|important\|Generally opt for the recommended {{FILE\|POTCAR}} files, but test if the property of interest is sensitive to the choice of the pseudopotential. It may be possible to choose a computationally cheaper version or necessary to select a more demanding one.\|:}}

	'''Step 5:''' For a single element in the structure, you can copy the {{FILE\|POTCAR}} to the working directory, e.g,		'''Step 5:''' For a single element in the structure, you can copy the {{FILE\|POTCAR}} to the working directory, e.g,
Line 27:		Line 24:
	cat ~/pot/Al/POTCAR ~/pot/C/POTCAR ~/pot/H/POTCAR > POTCAR		cat ~/pot/Al/POTCAR ~/pot/C/POTCAR ~/pot/H/POTCAR > POTCAR

	The order of the potentials must correspond to the order of the species in the {{FILE\|POSCAR}} file.		:The order of the potentials must correspond to the order of the species in the {{FILE\|POSCAR}} file.
	{{NB\|tip\|If species names are given in the {{FILE\|POSCAR}}, and the order does not match the order in the {{FILE\|POTCAR}}, a warning is printed, but VASP will still run.\|:}}		{{NB\|tip\|If species names are given in the {{FILE\|POSCAR}}, and the order does not match the order in the {{FILE\|POTCAR}}, a warning is printed, but VASP will still run.\|:}}

Huebsch: /* Step-by-step instructions */

2024-06-11T13:44:22Z

Step-by-step instructions

← Older revision		Revision as of 13:44, 11 June 2024
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	==Step-by-step instructions==		==Step-by-step instructions==

	'''Step 1:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]] ~~and version~~.		'''Step 1:''' Select the [[Available_pseudopotentials\|latest version]] of {{FILE\|POTCAR}} files unless you need to use an older one to reproduce a result.
	{{NB\|tip\|~~Amongst all [[Available PAW potentials\|available potentials]], the~~ standard choice is to use the ~~latest~~ GGA version based on {{TAG\|LEXCH}}{{=}}PE.\|:}}
			'''Step 2:''' Choose
			* [[Available_pseudopotentials#Standard_potentials\|standard potentials]] for calculations depending mainly on occupied states, e.g., within density-functional theory, or
			* [[Available_pseudopotentials#GW_potentials\|GW variants]] if the calculation requires high accuracy for unoccupied states, i.e., for [[optical properties\|optical response]] and [[many-body perturbation theory]].

			'''Step 3:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]].
			{{NB\|tip\|The standard choice is to use the [[Available_pseudopotentials#Standard_potentials\|GGA/PBE version]] based on {{TAG\|LEXCH}}{{=}}PE.\|:}}
	:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. One set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}. We recommend using the latest available potentials. Older versions are available to ensure reproducibility.		:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. One set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}. We recommend using the latest available potentials. Older versions are available to ensure reproducibility.

	'''Step 2:''' Choose a {{FILE\|POTCAR}} with a different atomic configuration, hard ~~or GW variant~~.		'''Step 4 (optional):''' Choose a {{FILE\|POTCAR}} with a different atomic configuration or hard version.
	{{NB\|tip\|The standard choice is to use the ~~plain~~ version ~~without suffixes~~.\|:}}		{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}
	:The suffix may correspond to a harder potential necessary to describe short bond lengths or a different number of valence electrons, e.g., required to describe magnetism, as well as higher accuracy for unoccupied states required for optical response and many-body perturbation theory. See [[~~Choosing pseudopotentials\|~~choosing pseudopotentials]].		:See [[choosing pseudopotentials]].

	'''Step 3:''' Combine the potentials.		'''Step 5:''' For a single element in the structure, you can copy the {{FILE\|POTCAR}} to the working directory, e.g,
			cp ~/pot/Al/POTCAR .
			:For structures with multiple elements, the selected {{FILE\|POTCAR}} files must be concatenated to create one {{FILE\|POTCAR}} file containing all species present in the structure. Combine the potentials by entering, for instance,
			cat ~/pot/Al/POTCAR ~/pot/C/POTCAR ~/pot/H/POTCAR > POTCAR

	~~:VASP expects a single {{FILE\|POTCAR}} file in the working directory containing all species present in the structure. The {{FILE\|POTCAR}} files must be concatenated.~~ The order of ~~files~~ must correspond to the order of the species in the {{FILE\|POSCAR}} file. If species names are given in the {{FILE\|POSCAR}}, and ~~they do~~ not match the order in the {{FILE\|POTCAR}}, a warning is printed, but VASP will still run. ~~The order given in the {{FILE~~\|~~POTCAR~~}} ~~will take precedence over the order in {{FILE\|POSCAR}}! You can copy the {{FILE\|POTCAR}} to the working directory if you have only one element in your structure.~~		The order of the potentials must correspond to the order of the species in the {{FILE\|POSCAR}} file.
			{{NB\|tip\|If species names are given in the {{FILE\|POSCAR}}, and the order does not match the order in the {{FILE\|POTCAR}}, a warning is printed, but VASP will still run.\|:}}

	==Recommendations and advice==		==Recommendations and advice==

Huebsch: Huebsch moved page Prepare a POTCAR to Preparing a POTCAR

2024-06-11T10:21:16Z

Huebsch moved page Prepare a POTCAR to Preparing a POTCAR

← Older revision	Revision as of 10:21, 11 June 2024
(No difference)

← Older revision		Revision as of 09:27, 12 June 2024
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	'''Step 2:''' Choose		'''Step 2:''' Choose
	* [[Available_pseudopotentials#Standard_potentials\|standard potentials]] for calculations depending mainly on occupied states, e.g., within density-functional theory, or		* [[Available_pseudopotentials#Standard_potentials\|standard potentials]] for calculations depending mainly on occupied states, e.g., within density-functional theory, using [[hybrid functionals]], or
	* [[Available_pseudopotentials#GW_potentials\|GW variants]] if the calculation requires high accuracy for unoccupied states, i.e., for [[optical properties\|optical response]] and [[many-body perturbation theory]].		* [[Available_pseudopotentials#GW_potentials\|GW variants]] if the calculation requires high accuracy for unoccupied states, i.e., for [[optical properties\|optical response]] and [[many-body perturbation theory]].

	'''Step 3:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]].		'''Step 3:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]].
	{{NB\|tip\|The standard choice is to use the [[Available_pseudopotentials#Standard_potentials\|~~GGA/~~PBE version]] based on {{TAG\|LEXCH}}{{=}}PE.\|:}}		{{NB\|tip\|The standard choice is to use the [[Available_pseudopotentials#Standard_potentials\|PBE version]] based on {{TAG\|LEXCH}}{{=}}PE which has a high transferability to other [[XC functionals]].\|:}}
	:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. ~~One~~ set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}~~. We recommend using the latest available potentials. Older versions are available to ensure reproducibility~~.		:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. In most versions, one set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}.

	'''Step 4 (optional):''' Choose a ~~{{FILE~~\|~~POTCAR}} with a~~ different atomic configuration ~~or hard version~~.		'''Step 4 (optional):''' Choose a [[Available pseudopotentials#Different variants specified by the suffix\|different variant (reference atomic valence configuration, etc.) specified by the suffix]].
	{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}		{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}
	:See [[choosing pseudopotentials]].		:See [[choosing pseudopotentials]].

← Older revision		Revision as of 14:37, 11 June 2024
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	{{NB\|mind\|You can mix and match {{FILE\|POTCAR}} families. Even combining pseudopotentials generated with different [[XC functionals]] is possible, however make sure to specify the [[XC functional]] in the {{FILE\|INCAR}}, see {{TAG\|XC}}.}}		{{NB\|mind\|You can mix and match {{FILE\|POTCAR}} families. Even combining pseudopotentials generated with different [[XC functionals]] is possible, however make sure to specify the [[XC functional]] in the {{FILE\|INCAR}}, see {{TAG\|XC}}.}}

	==Example for preparing a {{FILE\|POTCAR}} for the Heusler alloy TiCo<~~math~~>_2</~~math~~>Si==		==Example for preparing a {{FILE\|POTCAR}} for the Heusler alloy TiCo<sub>2</sub>Si==

	In this example, we want to prepare a {{FILE\|POTCAR}} for a PBE calculation of ferromagnetic TiCo<~~math~~>_2</~~math~~>Si. We are interested in the size of the magnetic moments.		In this example, we want to prepare a {{FILE\|POTCAR}} for a PBE calculation of ferromagnetic TiCo<sub>2</sub>Si. We are interested in the size of the magnetic moments.

	The structure is defined by the following {{FILE\|POSCAR}}:		The structure is defined by the following {{FILE\|POSCAR}}:

← Older revision		Revision as of 13:44, 11 June 2024
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	==Step-by-step instructions==		==Step-by-step instructions==

	'''Step 1:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]] ~~and version~~.		'''Step 1:''' Select the [[Available_pseudopotentials\|latest version]] of {{FILE\|POTCAR}} files unless you need to use an older one to reproduce a result.
	{{NB\|tip\|~~Amongst all [[Available PAW potentials\|available potentials]], the~~ standard choice is to use the ~~latest~~ GGA version based on {{TAG\|LEXCH}}{{=}}PE.\|:}}
			'''Step 2:''' Choose
			* [[Available_pseudopotentials#Standard_potentials\|standard potentials]] for calculations depending mainly on occupied states, e.g., within density-functional theory, or
			* [[Available_pseudopotentials#GW_potentials\|GW variants]] if the calculation requires high accuracy for unoccupied states, i.e., for [[optical properties\|optical response]] and [[many-body perturbation theory]].

			'''Step 3:''' Select a {{FILE\|POTCAR}} for a certain family of [[Exchange-correlation functionals\|exchange-correlation (XC) functionals]].
			{{NB\|tip\|The standard choice is to use the [[Available_pseudopotentials#Standard_potentials\|GGA/PBE version]] based on {{TAG\|LEXCH}}{{=}}PE.\|:}}
	:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. One set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}. We recommend using the latest available potentials. Older versions are available to ensure reproducibility.		:All potentials are constructed based on solving the scalar relativistic Schrödinger equation for a reference system with a certain [[Exchange-correlation functionals\|XC functional]]. One set is available for the LDA, and one for the GGA. The transferability to other [[Exchange-correlation functionals\|XC functionals]] is seamless by specifying the {{TAG\|XC}} tag in the {{FILE\|INCAR}}. We recommend using the latest available potentials. Older versions are available to ensure reproducibility.

	'''Step 2:''' Choose a {{FILE\|POTCAR}} with a different atomic configuration, hard ~~or GW variant~~.		'''Step 4 (optional):''' Choose a {{FILE\|POTCAR}} with a different atomic configuration or hard version.
	{{NB\|tip\|The standard choice is to use the ~~plain~~ version ~~without suffixes~~.\|:}}		{{NB\|tip\|The standard choice is to use the bold version in the [[Available pseudopotentials#Recommended PAW potentials\|list of PAW potentials]].\|:}}
	:The suffix may correspond to a harder potential necessary to describe short bond lengths or a different number of valence electrons, e.g., required to describe magnetism, as well as higher accuracy for unoccupied states required for optical response and many-body perturbation theory. See [[~~Choosing pseudopotentials\|~~choosing pseudopotentials]].		:See [[choosing pseudopotentials]].

	'''Step 3:''' Combine the potentials.		'''Step 5:''' For a single element in the structure, you can copy the {{FILE\|POTCAR}} to the working directory, e.g,
			cp ~/pot/Al/POTCAR .
			:For structures with multiple elements, the selected {{FILE\|POTCAR}} files must be concatenated to create one {{FILE\|POTCAR}} file containing all species present in the structure. Combine the potentials by entering, for instance,
			cat ~/pot/Al/POTCAR ~/pot/C/POTCAR ~/pot/H/POTCAR > POTCAR

	~~:VASP expects a single {{FILE\|POTCAR}} file in the working directory containing all species present in the structure. The {{FILE\|POTCAR}} files must be concatenated.~~ The order of ~~files~~ must correspond to the order of the species in the {{FILE\|POSCAR}} file. If species names are given in the {{FILE\|POSCAR}}, and ~~they do~~ not match the order in the {{FILE\|POTCAR}}, a warning is printed, but VASP will still run. ~~The order given in the {{FILE~~\|~~POTCAR~~}} ~~will take precedence over the order in {{FILE\|POSCAR}}! You can copy the {{FILE\|POTCAR}} to the working directory if you have only one element in your structure.~~		The order of the potentials must correspond to the order of the species in the {{FILE\|POSCAR}} file.
			{{NB\|tip\|If species names are given in the {{FILE\|POSCAR}}, and the order does not match the order in the {{FILE\|POTCAR}}, a warning is printed, but VASP will still run.\|:}}

	==Recommendations and advice==		==Recommendations and advice==