Setting up an electronic minimization - Revision history

Wolloch: /* Related tags and articles */

2025-03-27T12:59:13Z

Wolloch: /* Recommendations and advice */

2025-03-11T13:29:55Z

Recommendations and advice

← Older revision		Revision as of 13:29, 11 March 2025
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	{{NB\|mind\|Make sure to specify the lattice vectors and ionic positions in the {{FILE\|POSCAR}} with at least 7 digits of precision to ensure the [[POSCAR#Precision_and_symmetry\|symmetry analysis]] can function accurately.}}		{{NB\|mind\|Make sure to specify the lattice vectors and ionic positions in the {{FILE\|POSCAR}} with at least 7 digits of precision to ensure the [[POSCAR#Precision_and_symmetry\|symmetry analysis]] can function accurately.}}
	{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}		{{NB\|tip\|
	~~{{NB\|tip\|~~A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}		*Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.
	~~{{NB\|tip\|~~{{TAG\|ENCUT}} defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.}}		*A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.
	~~{{NB\|tip\|~~Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.}}		*{{TAG\|ENCUT}} defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.
	~~{{NB\|tip\|~~Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.}}		*Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.
			*Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.\|\|Tips}}

	== Example ==		== Example ==

Huebsch: /* References */

2025-03-11T10:14:41Z

References

← Older revision		Revision as of 10:14, 11 March 2025
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	== References ==		== References ==

	[[Category:Howto\|Howto]], [[Category:Calculation_setup\|Calculation setup]], [[Category:Electronic minimization\|Electronic minmization]]		[[Category:Howto\|Howto]] [[Category:Calculation_setup\|Calculation setup]] [[Category:Electronic minimization\|Electronic minmization]]

Huebsch at 10:12, 11 March 2025

2025-03-11T10:12:38Z

← Older revision		Revision as of 10:12, 11 March 2025
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	Setting up an [[:Category:Electronic minimization \|electronic minimization]] calculation using density-functional theory requires a few steps. The [[:Category:Input files \| input files]] must be created or copied into the execution folder. This includes making a few choices for the [[KPOINTS \| '''k'''-point]] sampling and [[ISMEAR \| electronic smearing]], [[ALGO \| minimization algorithm]], and [[:Category:Exchange-correlation functionals\|exchange-correlation functionals]]. A [[Command-line_arguments#--dry-run_/_-n \| dry-run]] can be used to review settings and select appropriate [[:Category:Parallelization \| parallelization]] tags. After running the calculation, the ~~[[OSZICAR \|~~ output]] can be analyzed.		Setting up an [[:Category:Electronic minimization \|electronic minimization]] calculation using density-functional theory requires a few steps. The [[:Category:Input files \| input files]] must be created or copied into the execution folder. This includes making a few choices for the [[KPOINTS \| '''k'''-point]] sampling and [[ISMEAR \| electronic smearing]], [[ALGO \| minimization algorithm]], and [[:Category:Exchange-correlation functionals\|exchange-correlation functionals]]. A [[Command-line_arguments#--dry-run_/_-n \| dry-run]] can be used to review settings and select appropriate [[:Category:Parallelization \| parallelization]] tags. After running the calculation, the output can be analyzed.

	== Step-by-step instructions ==		== Step-by-step instructions ==

Huebsch at 09:58, 11 March 2025

2025-03-11T09:58:24Z

← Older revision		Revision as of 09:58, 11 March 2025
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	'''Step 3''': Create a suitable {{FILE\|POTCAR}} file by following the instructions on our [[Preparing a POTCAR \| preparing a POTCAR]] page.		'''Step 3''': Create a suitable {{FILE\|POTCAR}} file by following the instructions on our [[Preparing a POTCAR \| preparing a POTCAR]] page.

	'''Step 4''': Create a {{FILE\| KPOINTS}} file to define the [[Integrating over all orbitals\|integration mesh in reciprocal space]]. Including a single k point at the origin, i.e. the Gamma point, neglects all interactions beyond the unit cell. This is appropriate for isolates systems like a single molecule or in large supercells. For bulk systems, start with a [[KPOINTS#Regular_k-point_mesh\|regular mesh]]. For shorter lattice vectors, more k points are required to achieve the same sampling density. Consult the [[KPOINTS#Symmetry_reduction_of_the_mesh \| symmetry reduction section]] of the {{FILE\| KPOINTS}} page to select the appropriate mesh type. Alternatively to a {{FILE\| KPOINTS}} file, the {{~~tag~~\| KSPACING}} can be used.		'''Step 4''': Create a {{FILE\| KPOINTS}} file to define the [[Integrating over all orbitals\|integration mesh in reciprocal space]]. Including a single k point at the origin, i.e. the Gamma point, neglects all interactions beyond the unit cell. This is appropriate for isolates systems like a single molecule or in large supercells. For bulk systems, start with a [[KPOINTS#Regular_k-point_mesh\|regular mesh]]. For shorter lattice vectors, more k points are required to achieve the same sampling density. Consult the [[KPOINTS#Symmetry_reduction_of_the_mesh \| symmetry reduction section]] of the {{FILE\| KPOINTS}} page to select the appropriate mesh type. Alternatively to a {{FILE\| KPOINTS}} file, the {{TAG\| KSPACING}} can be used.

	'''Step 5''': Write an {{FILE\| INCAR}} file. It is recommended to start from a rather minimal file, and only specify the most important tags:		'''Step 5''': Write an {{FILE\| INCAR}} file. It is recommended to start from a rather minimal file, and only specify the most important tags:
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	== References ==		== References ==


	[[Category:Howto\|Howto]], [[Category:Calculation_setup\|Calculation setup]], [[Category:Electronic minimization\|Electronic minmization]]		[[Category:Howto\|Howto]], [[Category:Calculation_setup\|Calculation setup]], [[Category:Electronic minimization\|Electronic minmization]]

Huebsch at 09:57, 11 March 2025

2025-03-11T09:57:45Z

← Older revision		Revision as of 09:57, 11 March 2025
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	[[:Category:Howto\|Howto]], [[:Category:Calculation_setup\|Calculation setup]], [[:Category:Electronic minimization\|Electronic minmization]]		[[Category:Howto\|Howto]], [[Category:Calculation_setup\|Calculation setup]], [[Category:Electronic minimization\|Electronic minmization]]

Huebsch: Huebsch moved page Construction:Setting up a DFT calculation to Setting up an electronic minimization without leaving a redirect

2025-03-11T09:57:09Z

Huebsch moved page Construction:Setting up a DFT calculation to Setting up an electronic minimization without leaving a redirect

← Older revision	Revision as of 09:57, 11 March 2025
(No difference)

Huebsch at 09:56, 11 March 2025

2025-03-11T09:56:14Z

Show changes

Huebsch at 08:44, 11 March 2025

2025-03-11T08:44:11Z

← Older revision		Revision as of 08:44, 11 March 2025
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	== Step-by-step instructions ==		== Step-by-step instructions ==

	~~'''Step 1''':~~ Create ~~a {{FILE\| POSCAR}} file containing~~ the ~~structure for which you want to compute the electronic groundstate. External Python tools like the Atomic Simulation Environment (ASE){{cite\|ase}} or pymatgen{{cite\|pymatgen}} can help with this step.~~		=== Create the input files ===

	'''Step 2''': ~~Choose an exchange-correlation~~ (XC) ~~functional appropriate for your material and quantity of interest according to our page recommending how to [[:Category:Exchange-correlation_functionals#Which_exchange-correlation_method_to_choose?~~ \| ~~choose an XC method]]~~.		'''Step 1''': Create a {{FILE\| POSCAR}} file containing the structure for which you want to compute the electronic groundstate. External tools like VESTA{{cite\|vesta}}, or Python packages like the Atomic Simulation Environment (ASE){{cite\|ase}} or pymatgen{{cite\|pymatgen}} can help with this step.

	'''Step 3''': ~~Create a suitable {{FILE\| POTCAR}} file by following the instructions on our~~ [[~~Preparing a POTCAR~~ \| ~~preparing a POTCAR~~]] ~~page~~.		'''Step 2''': [[:Category:Exchange-correlation_functionals#Which_exchange-correlation_method_to_choose?\|Choose an exchange-correlation (XC) functional]] appropriate for your material and quantity of interest.

	'''Step 4''': Create a {{FILE\| KPOINTS}} file to define the integration mesh in reciprocal space. ~~Starting~~ with a [[KPOINTS#Regular_k-point_mesh\| regular mesh]]~~is typically a good idea~~. Consult the [[KPOINTS#Symmetry_reduction_of_the_mesh \| symmetry reduction section]] of the {{FILE\| KPOINTS}} page to select the appropriate mesh type.		'''Step 3''': Create a suitable {{FILE\|POTCAR}} file by following the instructions on our [[Preparing a POTCAR \| preparing a POTCAR]] page.

			'''Step 4''': Create a {{FILE\| KPOINTS}} file to define the [[Integrating over all orbitals\|integration mesh in reciprocal space]]. Including a single k point at the origin, i.e. the Gamma point, neglects all interactions beyond the unit cell. This is appropriate for isolates systems like a single molecule or in large supercells. For bulk systems, start with a [[KPOINTS#Regular_k-point_mesh\|regular mesh]]. For shorter lattice vectors, more k points are required to achieve the same sampling density. Consult the [[KPOINTS#Symmetry_reduction_of_the_mesh \| symmetry reduction section]] of the {{FILE\| KPOINTS}} page to select the appropriate mesh type. Alternatively to a {{FILE\| KPOINTS}} file, the {{tag\| KSPACING}} can be used.

	'''Step 5''': Write an {{FILE\| INCAR}} file. It is recommended to start from a rather minimal file, and only specify the most important tags:		'''Step 5''': Write an {{FILE\| INCAR}} file. It is recommended to start from a rather minimal file, and only specify the most important tags:
	:* [[XC]] to specify the [[:Category:Exchange-correlation_functionals\| exchange-correlation functional]] ~~you want to use~~.		:* [[XC]] to specify the [[:Category:Exchange-correlation_functionals\| exchange-correlation functional]].
	:* [[ALGO]] to select the algorithm for [[:Category:Electronic minimization \|electronic minimization]].		:* [[ALGO]] to select the algorithm for [[:Category:Electronic minimization \|electronic minimization]].
	:* [[ISMEAR]] to select the type of [[Smearing technique\|electronic smearing technique]].		:* [[ISMEAR]] to select the type of [[Smearing technique\|electronic smearing technique]].
Line 19:		Line 21:
	:* [[EDIFF]] to specify the global break condition for the electronic self-consistent loop		:* [[EDIFF]] to specify the global break condition for the electronic self-consistent loop

	'''Step 6''' (optional): Select the appropriate version of the VASP executable. I.e. <code>vasp_gam</code> if you only want to use the Gamma point for reciprocal space integration, <code>vasp_ncl</code> for [[:Category:Noncollinear_magnetism\| noncollinear]] calculations, or <code>vasp_std</code> for anything else. Then Run a [[Command-line_arguments#--dry-run_/_-n \| dry-run]] calculation to validate settings and uncover possible errors.		=== Optimize your settings ===

			'''Step 6''' (optional): Select the appropriate version of the VASP executable. I.e. <code>vasp_gam</code> if you only want to use the Gamma point for reciprocal space integration, <code>vasp_ncl</code> for [[:Category:Noncollinear_magnetism\| noncollinear magnetic]] calculations, or <code>vasp_std</code> for anything else. Then Run a [[Command-line_arguments#--dry-run_/_-n \| dry-run]] calculation to validate settings and uncover possible errors. Open a terminal, go to the calculation directory that contains all input files and run

			/path/to/your/vasp_std --dry-run

			'''Step 7''' (optional): Inspect the {{FILE\| OUTCAR}} file of your [[Command-line_arguments#--dry-run_/_-n \| dry-run]]. Take note of the number of bands, {{TAG\|NBANDS}}, and the number of '''k'''-points, NKPTS, especially. Follow the guidelines on the [[Optimizing_the_parallelization \| optimizing the parallelization]] page to set {{TAG\|NCORE}} and/or {{TAG\|KPAR}} in the {{FILE\|INCAR}} file.

			=== Run the calculation ===

			'''Step 8''': Run the calculation. If you are new to VASP, or unsure about the calculation setup, run a small calculation and monitor the [[stdout \| screen output]]. For parallel execution on 4 MPI ranks, the command reads

			mpirun -np 4 /path/to/your/vasp_std

			At an HPC center, submit your job with a submission script. Ask your system administrator for help.

	~~'''Step 7''' (optional): Inspect~~ the ~~{{FILE\| OUTCAR}} file of your~~ [[~~Command~~-~~line_arguments#~~-~~-dry-run_/_-n~~ \| ~~dry-run~~]]. ~~Take note of~~ the ~~number of bands,~~ {{~~TAG~~\|~~NBANDS~~}}, ~~and the number of '''k'''-points, NKPTS, especially. Follow the guidelines on~~ the [[~~Optimizing_the_parallelization~~ \| ~~optimizing the parallelization~~]] ~~page to set {{TAG\|NCORE}}~~ and/~~or {{TAG~~\|~~KPAR}} in the {{FILE\| INCAR}} file~~.		Once the calculation is finished, you have access to the [[:Category:Electronic ground-state properties\| electronic ground-state properties]] via the [[:Category:Output_files\| output files]] for the selected parameters. Check the {{FILE\| OUTCAR}} file for warnings or advice. For help, consult the page about [[Troubleshooting_electronic_convergence\| troubleshooting electronic convergence]] and search our [https://www.vasp.at/forum/\| Forum] for similar issues.

	'''Step 8''': ~~Run the calculation~~. ~~If you are new to VASP, or unsure about the calculation setup~~, monitor the [[stdout \| screen output]]. Once the calculation is finished, you have access to the [[:Category:Electronic ground-state properties\| electronic ground state properties]] via the [[:Category:Output_files\| output files]]. ~~If there are problems with~~ the ~~[[:Category:Electronic_minimization\| electronic minimization]], consult~~ the page about [[Troubleshooting_electronic_convergence\| troubleshooting electronic convergence]]. If you can not solve your problems with these resources, search our [[https://www.vasp.at/forum/\| Forum]] for posts with similar issues.		'''Step 9''' (convergence study): Repeat Steps 4 - 8 with increasingly accurate parameter settings, e.g. higher cutoff energy and denser k-points mesh, and monitor your quantity of interest. Stop if the quantity of interest reaches the desired accuracy.

	== Recommendations and advice ==		== Recommendations and advice ==
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	{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}		{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}
	{{NB\|tip\|A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}		{{NB\|tip\|A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}
	{{NB\|tip\|[[ENCUT]] defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.}}		{{NB\|tip\|{{TAG\|ENCUT}} defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.}}
	{{NB\|tip\|Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.}}		{{NB\|tip\|Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.}}
	{{NB\|tip\|Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.}}		{{NB\|tip\|Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.}}

Wolloch: /* Recommendations and advice */

2025-03-10T11:28:04Z

Recommendations and advice

← Older revision		Revision as of 11:28, 10 March 2025
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	== Recommendations and advice ==		== Recommendations and advice ==

	{{NB\|mind\|Make sure to specify the lattice vectors and ionic positions in the {{FILE\|POSCAR}} with at least 7 digits of precision to ensure the [[POSCAR#Precision_and_symmetry\|symmetry analysis]] can ~~work~~ accurately.}}		{{NB\|mind\|Make sure to specify the lattice vectors and ionic positions in the {{FILE\|POSCAR}} with at least 7 digits of precision to ensure the [[POSCAR#Precision_and_symmetry\|symmetry analysis]] can function accurately.}}
	{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}		{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}
	{{NB\|tip\|A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}		{{NB\|tip\|A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}

← Older revision		Revision as of 12:59, 27 March 2025
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	[[:Category:Output_files\| Output files]] and [[:Category:Electronic ground-state properties\| Electronic ground-state properties]]		[[:Category:Output_files\| Output files]] and [[:Category:Electronic ground-state properties\| Electronic ground-state properties]]

			[[Category:Howto]]

	== References ==		== References ==

	[[Category:Howto\|Howto]] [[Category:Calculation_setup\|Calculation setup]] [[Category:Electronic minimization\|Electronic minmization]]		[[Category:Howto\|Howto]] [[Category:Calculation_setup\|Calculation setup]] [[Category:Electronic minimization\|Electronic minmization]]

← Older revision		Revision as of 13:29, 11 March 2025
Line 44:		Line 44:

	{{NB\|mind\|Make sure to specify the lattice vectors and ionic positions in the {{FILE\|POSCAR}} with at least 7 digits of precision to ensure the [[POSCAR#Precision_and_symmetry\|symmetry analysis]] can function accurately.}}		{{NB\|mind\|Make sure to specify the lattice vectors and ionic positions in the {{FILE\|POSCAR}} with at least 7 digits of precision to ensure the [[POSCAR#Precision_and_symmetry\|symmetry analysis]] can function accurately.}}
	{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}		{{NB\|tip\|
	~~{{NB\|tip\|~~A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}		*Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.
	~~{{NB\|tip\|~~{{TAG\|ENCUT}} defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.}}		*A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.
	~~{{NB\|tip\|~~Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.}}		*{{TAG\|ENCUT}} defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.
	~~{{NB\|tip\|~~Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.}}		*Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.
			*Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.\|\|Tips}}

	== Example ==		== Example ==

← Older revision		Revision as of 08:44, 11 March 2025
Line 3:		Line 3:
	== Step-by-step instructions ==		== Step-by-step instructions ==

	~~'''Step 1''':~~ Create ~~a {{FILE\| POSCAR}} file containing~~ the ~~structure for which you want to compute the electronic groundstate. External Python tools like the Atomic Simulation Environment (ASE){{cite\|ase}} or pymatgen{{cite\|pymatgen}} can help with this step.~~		=== Create the input files ===

	'''Step 2''': ~~Choose an exchange-correlation~~ (XC) ~~functional appropriate for your material and quantity of interest according to our page recommending how to [[:Category:Exchange-correlation_functionals#Which_exchange-correlation_method_to_choose?~~ \| ~~choose an XC method]]~~.		'''Step 1''': Create a {{FILE\| POSCAR}} file containing the structure for which you want to compute the electronic groundstate. External tools like VESTA{{cite\|vesta}}, or Python packages like the Atomic Simulation Environment (ASE){{cite\|ase}} or pymatgen{{cite\|pymatgen}} can help with this step.

	'''Step 3''': ~~Create a suitable {{FILE\| POTCAR}} file by following the instructions on our~~ [[~~Preparing a POTCAR~~ \| ~~preparing a POTCAR~~]] ~~page~~.		'''Step 2''': [[:Category:Exchange-correlation_functionals#Which_exchange-correlation_method_to_choose?\|Choose an exchange-correlation (XC) functional]] appropriate for your material and quantity of interest.

	'''Step 4''': Create a {{FILE\| KPOINTS}} file to define the integration mesh in reciprocal space. ~~Starting~~ with a [[KPOINTS#Regular_k-point_mesh\| regular mesh]]~~is typically a good idea~~. Consult the [[KPOINTS#Symmetry_reduction_of_the_mesh \| symmetry reduction section]] of the {{FILE\| KPOINTS}} page to select the appropriate mesh type.		'''Step 3''': Create a suitable {{FILE\|POTCAR}} file by following the instructions on our [[Preparing a POTCAR \| preparing a POTCAR]] page.

			'''Step 4''': Create a {{FILE\| KPOINTS}} file to define the [[Integrating over all orbitals\|integration mesh in reciprocal space]]. Including a single k point at the origin, i.e. the Gamma point, neglects all interactions beyond the unit cell. This is appropriate for isolates systems like a single molecule or in large supercells. For bulk systems, start with a [[KPOINTS#Regular_k-point_mesh\|regular mesh]]. For shorter lattice vectors, more k points are required to achieve the same sampling density. Consult the [[KPOINTS#Symmetry_reduction_of_the_mesh \| symmetry reduction section]] of the {{FILE\| KPOINTS}} page to select the appropriate mesh type. Alternatively to a {{FILE\| KPOINTS}} file, the {{tag\| KSPACING}} can be used.

	'''Step 5''': Write an {{FILE\| INCAR}} file. It is recommended to start from a rather minimal file, and only specify the most important tags:		'''Step 5''': Write an {{FILE\| INCAR}} file. It is recommended to start from a rather minimal file, and only specify the most important tags:
	:* [[XC]] to specify the [[:Category:Exchange-correlation_functionals\| exchange-correlation functional]] ~~you want to use~~.		:* [[XC]] to specify the [[:Category:Exchange-correlation_functionals\| exchange-correlation functional]].
	:* [[ALGO]] to select the algorithm for [[:Category:Electronic minimization \|electronic minimization]].		:* [[ALGO]] to select the algorithm for [[:Category:Electronic minimization \|electronic minimization]].
	:* [[ISMEAR]] to select the type of [[Smearing technique\|electronic smearing technique]].		:* [[ISMEAR]] to select the type of [[Smearing technique\|electronic smearing technique]].
Line 19:		Line 21:
	:* [[EDIFF]] to specify the global break condition for the electronic self-consistent loop		:* [[EDIFF]] to specify the global break condition for the electronic self-consistent loop

	'''Step 6''' (optional): Select the appropriate version of the VASP executable. I.e. <code>vasp_gam</code> if you only want to use the Gamma point for reciprocal space integration, <code>vasp_ncl</code> for [[:Category:Noncollinear_magnetism\| noncollinear]] calculations, or <code>vasp_std</code> for anything else. Then Run a [[Command-line_arguments#--dry-run_/_-n \| dry-run]] calculation to validate settings and uncover possible errors.		=== Optimize your settings ===

			'''Step 6''' (optional): Select the appropriate version of the VASP executable. I.e. <code>vasp_gam</code> if you only want to use the Gamma point for reciprocal space integration, <code>vasp_ncl</code> for [[:Category:Noncollinear_magnetism\| noncollinear magnetic]] calculations, or <code>vasp_std</code> for anything else. Then Run a [[Command-line_arguments#--dry-run_/_-n \| dry-run]] calculation to validate settings and uncover possible errors. Open a terminal, go to the calculation directory that contains all input files and run

			/path/to/your/vasp_std --dry-run

			'''Step 7''' (optional): Inspect the {{FILE\| OUTCAR}} file of your [[Command-line_arguments#--dry-run_/_-n \| dry-run]]. Take note of the number of bands, {{TAG\|NBANDS}}, and the number of '''k'''-points, NKPTS, especially. Follow the guidelines on the [[Optimizing_the_parallelization \| optimizing the parallelization]] page to set {{TAG\|NCORE}} and/or {{TAG\|KPAR}} in the {{FILE\|INCAR}} file.

			=== Run the calculation ===

			'''Step 8''': Run the calculation. If you are new to VASP, or unsure about the calculation setup, run a small calculation and monitor the [[stdout \| screen output]]. For parallel execution on 4 MPI ranks, the command reads

			mpirun -np 4 /path/to/your/vasp_std

			At an HPC center, submit your job with a submission script. Ask your system administrator for help.

	~~'''Step 7''' (optional): Inspect~~ the ~~{{FILE\| OUTCAR}} file of your~~ [[~~Command~~-~~line_arguments#~~-~~-dry-run_/_-n~~ \| ~~dry-run~~]]. ~~Take note of~~ the ~~number of bands,~~ {{~~TAG~~\|~~NBANDS~~}}, ~~and the number of '''k'''-points, NKPTS, especially. Follow the guidelines on~~ the [[~~Optimizing_the_parallelization~~ \| ~~optimizing the parallelization~~]] ~~page to set {{TAG\|NCORE}}~~ and/~~or {{TAG~~\|~~KPAR}} in the {{FILE\| INCAR}} file~~.		Once the calculation is finished, you have access to the [[:Category:Electronic ground-state properties\| electronic ground-state properties]] via the [[:Category:Output_files\| output files]] for the selected parameters. Check the {{FILE\| OUTCAR}} file for warnings or advice. For help, consult the page about [[Troubleshooting_electronic_convergence\| troubleshooting electronic convergence]] and search our [https://www.vasp.at/forum/\| Forum] for similar issues.

	'''Step 8''': ~~Run the calculation~~. ~~If you are new to VASP, or unsure about the calculation setup~~, monitor the [[stdout \| screen output]]. Once the calculation is finished, you have access to the [[:Category:Electronic ground-state properties\| electronic ground state properties]] via the [[:Category:Output_files\| output files]]. ~~If there are problems with~~ the ~~[[:Category:Electronic_minimization\| electronic minimization]], consult~~ the page about [[Troubleshooting_electronic_convergence\| troubleshooting electronic convergence]]. If you can not solve your problems with these resources, search our [[https://www.vasp.at/forum/\| Forum]] for posts with similar issues.		'''Step 9''' (convergence study): Repeat Steps 4 - 8 with increasingly accurate parameter settings, e.g. higher cutoff energy and denser k-points mesh, and monitor your quantity of interest. Stop if the quantity of interest reaches the desired accuracy.

	== Recommendations and advice ==		== Recommendations and advice ==
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	{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}		{{NB\|tip\|Add only necessary tags to your {{FILE\|INCAR}} file. Cluttered input is a common source of mismatched settings.}}
	{{NB\|tip\|A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}		{{NB\|tip\|A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.}}
	{{NB\|tip\|[[ENCUT]] defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.}}		{{NB\|tip\|{{TAG\|ENCUT}} defaults to the largest [[ENMAX]] value found in the {{FILE\| POTCAR}} file. Still, it is always a good idea to include it in the {{FILE\| INCAR}} file to ensure comparability between different calculations.}}
	{{NB\|tip\|Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.}}		{{NB\|tip\|Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAGO\|ALGO\|None}} to check the feasibility of your settings and [[Optimizing_the_parallelization\| optimize parallelization tags]], without wasting computational resources.}}
	{{NB\|tip\|Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.}}		{{NB\|tip\|Some warnings are a bit hidden in the [[Screen_output#The_header\| header]] section of the [[Screen_output\| screen output]]. Redirecting the screen output to a file and saving it can simplify troubleshooting significantly.}}