Calculation of atoms - Revision history

Miranda.henrique: /* Determining the groundstate energ of atoms */

2021-07-19T14:12:49Z

Determining the groundstate energ of atoms

← Older revision		Revision as of 14:12, 19 July 2021
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	== Determining the groundstate ~~energ~~ of atoms ==		== Determining the groundstate energy of atoms ==

	The {{TAG\|POTCAR}} file contains information on the energy of the atom in the reference configuration (i.e. the configuration for which the pseudopotential was generated). Total energies calculated by VASP are with respect to this configuration. The reference calculation, however, did not allow for spin-polarisation or broken symmetry solutions, which usually lower the energy for gradient corrected of hybrid functionals. To include these effects properly, it is required to calculate the lowest energy magnetic groundstate using VASP.		The {{TAG\|POTCAR}} file contains information on the energy of the atom in the reference configuration (i.e. the configuration for which the pseudopotential was generated). Total energies calculated by VASP are with respect to this configuration. The reference calculation, however, did not allow for spin-polarisation or broken symmetry solutions, which usually lower the energy for gradient corrected of hybrid functionals. To include these effects properly, it is required to calculate the lowest energy magnetic groundstate using VASP.

Karsai at 07:55, 7 June 2021

2021-06-07T07:55:37Z

← Older revision		Revision as of 07:55, 7 June 2021
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	#DOS related values		#DOS related values
	{{TAGBL\|ISMEAR}} = 0		{{TAGBL\|ISMEAR}} = 0
	{{TAGBL\|SIGMA=0.1}} #use smearing method		{{TAGBL\|SIGMA}} = 0.1 #use smearing method

	The only difference to the bulk calculation is that Gaussian smearing must be used now. You might set {{TAG\|SIGMA}} to a very small value; this is necessary if atomic orbitals are almost degenerated. Another important point is spin polarization which can also lead to different energies in many cases. To turn on spin polarization additionally set {{TAG\|ISPIN}}=2 in the {{TAG\|INCAR}} file.		The only difference to the bulk calculation is that Gaussian smearing must be used now. You might set {{TAG\|SIGMA}} to a very small value; this is necessary if atomic orbitals are almost degenerated. Another important point is spin polarization which can also lead to different energies in many cases. To turn on spin polarization additionally set {{TAG\|ISPIN}}=2 in the {{TAG\|INCAR}} file.

Karsai at 13:28, 25 June 2019

2019-06-25T13:28:02Z

← Older revision		Revision as of 13:28, 25 June 2019
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	----		----

	[[Category:Atoms and Molecules]][[Category:Howto]]		[[Category:Atoms and Molecules]][[Category:Howto]]

Karsai: /* Determining the groundstate energ of atoms */

2019-06-24T17:20:25Z

Determining the groundstate energ of atoms

← Older revision		Revision as of 17:20, 24 June 2019
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	{{TAGBL\|ALGO}} = A		{{TAGBL\|ALGO}} = A
	{{TAGBL\|LSUBROT}} = .FALSE.		{{TAGBL\|LSUBROT}} = .FALSE.
	{{~~TAGLB~~\|NELM}} = 500		{{TAGBL\|NELM}} = 500
	{{TAGBL\|TIME}} = 0.2		{{TAGBL\|TIME}} = 0.2

Karsai: /* Determining the groundstate energ of atoms */

2019-06-24T17:20:14Z

Determining the groundstate energ of atoms

← Older revision		Revision as of 17:20, 24 June 2019
Line 93:		Line 93:
	{{TAGBL\|ICHARG}} = 1		{{TAGBL\|ICHARG}} = 1

	Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. <math>12.000 </math> <math>\AA</math> <math> \times </math> <math>12.001</math> <math>\AA</math> <math>\times</math> <math>12.~~001~~</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing		Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. <math>12.000 </math> <math>\AA</math> <math> \times </math> <math>12.001</math> <math>\AA</math> <math>\times</math> <math>12.002</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing

	{{TAGBL\|ALGO}} = D		{{TAGBL\|ALGO}} = D

Karsai: /* Determining the groundstate energ of atoms */

2019-06-24T17:20:03Z

Determining the groundstate energ of atoms

← Older revision		Revision as of 17:20, 24 June 2019
Line 93:		Line 93:
	{{TAGBL\|ICHARG}} = 1		{{TAGBL\|ICHARG}} = 1

	Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. 12.000 <math>\AA</math> <math> \times </math> <math>12.001</math> <math>\AA</math> <math>\times</math> <math>12.001</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing		Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. <math>12.000 </math> <math>\AA</math> <math> \times </math> <math>12.001</math> <math>\AA</math> <math>\times</math> <math>12.001</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing

	{{TAGBL\|ALGO}} = D		{{TAGBL\|ALGO}} = D

Karsai: /* Determining the groundstate energ of atoms */

2019-06-24T17:19:40Z

Determining the groundstate energ of atoms

← Older revision		Revision as of 17:19, 24 June 2019
Line 93:		Line 93:
	{{TAGBL\|ICHARG}} = 1		{{TAGBL\|ICHARG}} = 1

	Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. 12.000 <math>\AA</math> <math> \times </math> <math>12.001</math> <math>Å</math> <math>\times</math> <math>12.001</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing		Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. 12.000 <math>\AA</math> <math> \times </math> <math>12.001</math> <math>\AA</math> <math>\times</math> <math>12.001</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing

	{{TAGBL\|ALGO}} = D		{{TAGBL\|ALGO}} = D

Karsai: /* Determining the groundstate energ of atoms */

2019-06-24T17:19:09Z

Determining the groundstate energ of atoms

← Older revision		Revision as of 17:19, 24 June 2019
Line 93:		Line 93:
	{{TAGBL\|ICHARG}} = 1		{{TAGBL\|ICHARG}} = 1

	Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. 12.000 <math>\AA</math> <math> \times </math> <math>12.001<math> <math>Å</math> <math>\times</math> <math>12.001</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing		Execute VASP twice to three times, consecutively with this input file until energies are converged. Furthermore, we recommend to use large slightly non-cubic cells, i.e. 12.000 <math>\AA</math> <math> \times </math> <math>12.001</math> <math>Å</math> <math>\times</math> <math>12.001</math> <math>\AA</math>. In some cases, we also found it advantageously to use direct energy minimization instead of charge-density mixing

	{{TAGBL\|ALGO}} = D		{{TAGBL\|ALGO}} = D

Karsai at 17:18, 24 June 2019

2019-06-24T17:18:45Z

@@ Line 74: / Line 74: @@
   0  0
 The reasons for this behaviour are: Due to the finite size of the cell a band dispersion exists i.e. the atomic eigenvalues split and form a band with finite width. To first order the center of the band lies exactly at the position of the atomic eigenvalues. Using the <math>\Gamma</math>-point the eigenvalues at the bottom of the band are obtained. If the special point (0.25,0.25,0.25) 2<math>\pi/a</math> is used instead of the <math>\Gamma</math>-point, the energy of the center of the band is obtained. Nevertheless we recommend this setting only for absolute experts: in most cases the degeneracy of the p- and d-orbitals is removed and only the mean value of the eigenvalues remains physically significant. In this cases it is also necessary to increase {{TAG|SIGMA}} or to set the partial occupancies by hand!
 ----
 [[Category:Atoms and Molecules]][[Category:Howto]]

Karsai at 15:18, 24 June 2019

2019-06-24T15:18:19Z

← Older revision		Revision as of 15:18, 24 June 2019
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	{{TAGBL\|SYSTEM}} = Pd: atom		{{TAGBL\|SYSTEM}} = Pd: atom
	#Electronic minimisation		#Electronic minimisation
	{{~~TAGBK~~\|ENCUT}} = 200.00 eV #energy cut-off for the calculation		{{TAGBL\|ENCUT}} = 200.00 eV #energy cut-off for the calculation
	{{TAGBL\|EDIFF}} = 1E-04 #stopping-criterion for ELM		{{TAGBL\|EDIFF}} = 1E-04 #stopping-criterion for ELM
	{{TAGBL\|NELMDL}} = 5		{{TAGBL\|NELMDL}} = 5

← Older revision		Revision as of 17:20, 24 June 2019
Line 104:		Line 104:
	{{TAGBL\|ALGO}} = A		{{TAGBL\|ALGO}} = A
	{{TAGBL\|LSUBROT}} = .FALSE.		{{TAGBL\|LSUBROT}} = .FALSE.
	{{~~TAGLB~~\|NELM}} = 500		{{TAGBL\|NELM}} = 500
	{{TAGBL\|TIME}} = 0.2		{{TAGBL\|TIME}} = 0.2

← Older revision		Revision as of 15:18, 24 June 2019
Line 45:		Line 45:
	{{TAGBL\|SYSTEM}} = Pd: atom		{{TAGBL\|SYSTEM}} = Pd: atom
	#Electronic minimisation		#Electronic minimisation
	{{~~TAGBK~~\|ENCUT}} = 200.00 eV #energy cut-off for the calculation		{{TAGBL\|ENCUT}} = 200.00 eV #energy cut-off for the calculation
	{{TAGBL\|EDIFF}} = 1E-04 #stopping-criterion for ELM		{{TAGBL\|EDIFF}} = 1E-04 #stopping-criterion for ELM
	{{TAGBL\|NELMDL}} = 5		{{TAGBL\|NELMDL}} = 5