Setting up an electronic minimization - Revision history

Singraber at 08:10, 24 October 2025

2025-10-24T08:10:39Z

Ftran at 13:07, 13 October 2025

2025-10-13T13:07:47Z

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	:* [[ISMEAR]] to select the type of [[Smearing technique\|electronic smearing technique]].		:* [[ISMEAR]] to select the type of [[Smearing technique\|electronic smearing technique]].
	:* [[SIGMA]] to choose an appropriate smearing width of the [[Smearing technique\|electronic smearing]].		:* [[SIGMA]] to choose an appropriate smearing width of the [[Smearing technique\|electronic smearing]].
	:* [[ENCUT]] to set the plane-wave energy cutoff.		:* [[ENCUT]] to set the [[Energy_cut_off_and_FFT_mesh\|plane-wave energy cutoff]].
	:* [[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

Ftran at 12:00, 13 October 2025

2025-10-13T12:00:08Z

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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 minimization]]

Wolloch: /* Related tags and articles */

2025-03-27T12:59:13Z

Wolloch: /* Recommendations and advice */

2025-03-11T13:29:55Z

Recommendations and advice

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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

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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

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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

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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

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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)

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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
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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 ==

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	*A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.		*A larger smearing width {{TAG\|SIGMA}} might be required to converge the calculation if your {{FILE\| KPOINTS}} mesh is sparse.
	*{{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.		*{{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.
	*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.		*Use the [[Command-line_arguments#--dry-run_/_-n\| dry-run]] command-line argument or {{TAG\|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}}		*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 ==

	We will do a small DFT calculation of GaAs in the zincblende structure, using the local-density approximation (LDA) with the Perdew-Zunger parametrization of Ceperley-Alder Monte Carlo correlation data.{{cite\|ceperley1980}}{{cite\|perdewzunger1981}}. Thus, our [[:Category:Exchange-correlation_functionals\| XC functional]] will be set to {{~~TAGO~~\|XC\|CA}}.		We will do a small DFT calculation of GaAs in the zincblende structure, using the local-density approximation (LDA) with the Perdew-Zunger parametrization of Ceperley-Alder Monte Carlo correlation data.{{cite\|ceperley1980}}{{cite\|perdewzunger1981}}. Thus, our [[:Category:Exchange-correlation_functionals\| XC functional]] will be set to {{TAG\|XC\|CA}}.

	=== Setting up the {{FILE\|POSCAR}} file ===		=== Setting up the {{FILE\|POSCAR}} file ===
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	=== Creating the {{FILE\|POTCAR}} file ===		=== Creating the {{FILE\|POTCAR}} file ===

	We have already decided to use {{~~TAGO~~\|XC\|CA}}, and can create the {{FILE\|POTCAR}} file as discussed on the [[Preparing_a_POTCAR\| preparing a POTCAR]] page.		We have already decided to use {{TAG\|XC\|CA}}, and can create the {{FILE\|POTCAR}} file as discussed on the [[Preparing_a_POTCAR\| preparing a POTCAR]] page.

	=== Creating the {{FILE\|KPOINTS}} file ===		=== Creating the {{FILE\|KPOINTS}} file ===
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	=== Creating the {{FILE\|INCAR}} file ===		=== Creating the {{FILE\|INCAR}} file ===

	We chose the efficient combination of a [[blocked-Davidson algorithm]] and the [[RMM-DIIS]] algorithm which can be selected with {{~~TAGO~~\|ALGO\|Fast}}.		We chose the efficient combination of a [[blocked-Davidson algorithm]] and the [[RMM-DIIS]] algorithm which can be selected with {{TAG\|ALGO\|Fast}}.
	{{TAGBL\|ALGO}} = Fast		{{TAGBL\|ALGO}} = Fast
	GaAs is a semiconductor, so we could use the tetrahedron method {{~~TAGO~~\|ISMEAR\|-5}}, but bandgaps are underestimated systematically by DFT and XC functional or lattice parameter may fail to reproduce experimental results. Thus, following the recommendation on [[smearing technique#Which method to use \|electronic smearing techniques]], it is safer to select Gaussian smearing and a small smearing width:		GaAs is a semiconductor, so we could use the tetrahedron method {{TAG\|ISMEAR\|-5}}, but bandgaps are underestimated systematically by DFT and XC functional or lattice parameter may fail to reproduce experimental results. Thus, following the recommendation on [[smearing technique#Which method to use \|electronic smearing techniques]], it is safer to select Gaussian smearing and a small smearing width:
	{{TAGBL\|ISMEAR}} = 0		{{TAGBL\|ISMEAR}} = 0
	{{TAGBL\|SIGMA}} = 0.1		{{TAGBL\|SIGMA}} = 0.1
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	Which will print a warning about the [[Command-line_arguments#--dry-run_/_-n \| dry-run]] and some information about the MPI-ranks, OMP-threads, the VASP version, and the input structure. Mistakes in the setup, e.g. if the order of elements in the {{FILE\| POSCAR}} and {{FILE\| POTCAR}} do not match, warnings are printed.		Which will print a warning about the [[Command-line_arguments#--dry-run_/_-n \| dry-run]] and some information about the MPI-ranks, OMP-threads, the VASP version, and the input structure. Mistakes in the setup, e.g. if the order of elements in the {{FILE\| POSCAR}} and {{FILE\| POTCAR}} do not match, warnings are printed.

	We can now check the {{FILE\| OUTCAR}} file and find the total number of '''k'''-points, 20, and number of bands ({{TAG\|NBANDS}}), 13. This means a relatively low number of bands and a decent number of '''k''' points. If we want to run our calculation on 4 MPI ranks, setting {{~~TAGO~~\|KPAR\|4}} is an excellent choice for parallelization. Mind that the [[NBANDS#Parallelization\|parallelization changes number of bands]].		We can now check the {{FILE\| OUTCAR}} file and find the total number of '''k'''-points, 20, and number of bands ({{TAG\|NBANDS}}), 13. This means a relatively low number of bands and a decent number of '''k''' points. If we want to run our calculation on 4 MPI ranks, setting {{TAG\|KPAR\|4}} is an excellent choice for parallelization. Mind that the [[NBANDS#Parallelization\|parallelization changes number of bands]].

	=== Running the calculation ===		=== Running the calculation ===
	After adding {{~~TAGO~~\|KPAR\|4}} to the {{FILE\| INCAR}} file, we run the calculation on 4 MPI ranks:		After adding {{TAG\|KPAR\|4}} to the {{FILE\| INCAR}} file, we run the calculation on 4 MPI ranks:
	mpirun -np 4 /your/vasp_dir/bin/vasp_std		mpirun -np 4 /your/vasp_dir/bin/vasp_std
	Consult the page on [[screen output]] for details about the information VASP prints out. For this example it should be similar to this:		Consult the page on [[screen output]] for details about the information VASP prints out. For this example it should be similar to this: