LSORBIT - Revision history

Singraber at 15:56, 13 January 2025

2025-01-13T15:56:21Z

← Older revision		Revision as of 15:56, 13 January 2025
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	-0.0000000 -0.0000000 -0.0000000 0.0000000 -0.0000000 0.0000000 -0.0000000		-0.0000000 -0.0000000 -0.0000000 0.0000000 -0.0000000 0.0000000 -0.0000000
	-0.0000000 -0.0000000 0.0000000 0.0000000 0.0000000 -0.0000000 0.0000000		-0.0000000 -0.0000000 0.0000000 0.0000000 0.0000000 -0.0000000 0.0000000
	:Here, <code>1 E_soc</code> represents the accumulated energy contribution <math>E_{soc}=\sum_{ij} E_{soc}^{ij}</math> inside the augmentation sphere that is centered at <math>{\bf R}_1</math> (position of ion 1), while the following entries correspond to the matrix elements <math>E_{soc}^{ij}</math> for the angular momentum <math>l</math>.		:Here, <code>1 E_soc</code> represents the accumulated energy contribution <math>E_{soc}=\sum_{ij} E_{soc}^{ij}</math> inside the augmentation sphere that is centered at <math>{\bf R}_1</math> (position of ion 1), while the following entries correspond to the matrix elements <math>E_{soc}^{ij}</math> for the angular momentum <math>l</math>. Rows and columns correspond to <math>m</math> and <math>m'</math> of the real spherical harmonics <math>Y_{lm}</math>(see [[Angular functions]] for naming and ordering conventions).

	== Symmetry and convergence ==		== Symmetry and convergence ==

Huebsch at 12:10, 25 September 2023

2023-09-25T12:10:49Z

Show changes

Kresse at 08:30, 20 September 2023

2023-09-20T08:30:36Z

← Older revision		Revision as of 08:30, 20 September 2023
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	VASP reads in the {{FILE\|WAVECAR}} and {{FILE\|CHGCAR}} files, aligns the spin quantization axis parallel to {{TAG\|SAXIS}}, which implies that the magnetic field is now parallel to {{TAG\|SAXIS}}, and performs a non selfconsistent calculation. By comparing the energies for different orientations the magnetic anisotropy can be determined. Please mind, that a completely selfconsistent calculation ({{TAG\|ICHARG}} = 1) is in principle also possible with VASP, but this would allow the spinor wavefunctions to rotate from their initial orientation parallel to {{TAG\|SAXIS}} until the correct groundstate is obtained, i.e. until the magnetic moment is parallel to the easy axis. In practice this rotation will be slow, however, since reorientation of the spin gains little energy. Therefore if the convergence criterion is not too tight, sensible results might be obtained even for fully selfconsistent calculations (in the few cases we have tried this worked beautifully).		VASP reads in the {{FILE\|WAVECAR}} and {{FILE\|CHGCAR}} files, aligns the spin quantization axis parallel to {{TAG\|SAXIS}}, which implies that the magnetic field is now parallel to {{TAG\|SAXIS}}, and performs a non selfconsistent calculation. By comparing the energies for different orientations the magnetic anisotropy can be determined. Please mind, that a completely selfconsistent calculation ({{TAG\|ICHARG}} = 1) is in principle also possible with VASP, but this would allow the spinor wavefunctions to rotate from their initial orientation parallel to {{TAG\|SAXIS}} until the correct groundstate is obtained, i.e. until the magnetic moment is parallel to the easy axis. In practice this rotation will be slow, however, since reorientation of the spin gains little energy. Therefore if the convergence criterion is not too tight, sensible results might be obtained even for fully selfconsistent calculations (in the few cases we have tried this worked beautifully).

	*Be very careful with symmetry. When spin-orbit coupling is selected, we recommend to test whether switching off symmetry altogether ({{TAG\|ISYM}}=-1) changes the results. Often the k-point set changes from one to the other spin orientation, worsening the transferability of the results (also the {{FILE\|WAVECAR}} file can not be reread properly if the number of k-points changes). Additionally VASP.4.6 (and all older versions) had a bug in the symmetrization of magnetic fields (fixed only VASP.4.6.23). Although, we are confident that the present code base is free of errors in the symmetrization, it is recommended to double check the results without symmetry.		*Be very careful with symmetry. When spin-orbit coupling is selected, we recommend to test whether switching off symmetry altogether ({{TAG\|ISYM}}=-1) changes the results. Often the k-point set changes from one to the other spin orientation, worsening the transferability of the results (also the {{FILE\|WAVECAR}} file can not be reread properly if the number of k-points changes). Additionally, VASP.4.6 (and all older versions) had a bug in the symmetrization of magnetic fields (fixed only VASP.4.6.23). Although we are confident that the present code base is free of errors in the symmetrization, it is recommended to double check the results without symmetry.

	*Generally be extremely careful, when using spin-orbit coupling: energy differences are tiny, k-point convergence is tedious and slow, and the computer time you require might be ~~infinite~~.		*Generally, be extremely careful when using spin-orbit coupling: energy differences are tiny, k-point convergence is tedious and slow, and the computer time you require might be huge even for small cells.

	*It is recommended to set {{TAG\|GGA_COMPAT}} = .FALSE. for non collinear calculations ~~in VASP.4.6~~, since this improves the numerical precision of GGA calculations.		*It is recommended to set {{TAG\|GGA_COMPAT}} = .FALSE. for non-collinear calculations, since this improves the numerical precision of GGA calculations.

	== Assumptions and output ==		== Assumptions and output ==

Kresse: Rephrased paragraph where switching off symmetry is recommended.

2023-09-20T08:26:05Z

Rephrased paragraph where switching off symmetry is recommended.

← Older revision		Revision as of 08:26, 20 September 2023
Line 93:		Line 93:
	VASP reads in the {{FILE\|WAVECAR}} and {{FILE\|CHGCAR}} files, aligns the spin quantization axis parallel to {{TAG\|SAXIS}}, which implies that the magnetic field is now parallel to {{TAG\|SAXIS}}, and performs a non selfconsistent calculation. By comparing the energies for different orientations the magnetic anisotropy can be determined. Please mind, that a completely selfconsistent calculation ({{TAG\|ICHARG}} = 1) is in principle also possible with VASP, but this would allow the spinor wavefunctions to rotate from their initial orientation parallel to {{TAG\|SAXIS}} until the correct groundstate is obtained, i.e. until the magnetic moment is parallel to the easy axis. In practice this rotation will be slow, however, since reorientation of the spin gains little energy. Therefore if the convergence criterion is not too tight, sensible results might be obtained even for fully selfconsistent calculations (in the few cases we have tried this worked beautifully).		VASP reads in the {{FILE\|WAVECAR}} and {{FILE\|CHGCAR}} files, aligns the spin quantization axis parallel to {{TAG\|SAXIS}}, which implies that the magnetic field is now parallel to {{TAG\|SAXIS}}, and performs a non selfconsistent calculation. By comparing the energies for different orientations the magnetic anisotropy can be determined. Please mind, that a completely selfconsistent calculation ({{TAG\|ICHARG}} = 1) is in principle also possible with VASP, but this would allow the spinor wavefunctions to rotate from their initial orientation parallel to {{TAG\|SAXIS}} until the correct groundstate is obtained, i.e. until the magnetic moment is parallel to the easy axis. In practice this rotation will be slow, however, since reorientation of the spin gains little energy. Therefore if the convergence criterion is not too tight, sensible results might be obtained even for fully selfconsistent calculations (in the few cases we have tried this worked beautifully).

	*Be very careful with symmetry. We recommend to ~~switch~~ off symmetry altogether ({{TAG\|ISYM}}=-1)~~, when spin-orbit coupling is selected~~. Often the k-point set changes from one to the other spin orientation, worsening the transferability of the results (also the {{FILE\|WAVECAR}} file can not be reread properly if the number of k-points changes). Additionally VASP.4.6 (and all older versions) had a bug in the symmetrization of magnetic fields (fixed only VASP.4.6.23).		*Be very careful with symmetry. When spin-orbit coupling is selected, we recommend to test whether switching off symmetry altogether ({{TAG\|ISYM}}=-1) changes the results. Often the k-point set changes from one to the other spin orientation, worsening the transferability of the results (also the {{FILE\|WAVECAR}} file can not be reread properly if the number of k-points changes). Additionally VASP.4.6 (and all older versions) had a bug in the symmetrization of magnetic fields (fixed only VASP.4.6.23). Although, we are confident that the present code base is free of errors in the symmetrization, it is recommended to double check the results without symmetry.

	*Generally be extremely careful, when using spin-orbit coupling: energy differences are tiny, k-point convergence is tedious and slow, and the computer time you require might be infinite.		*Generally be extremely careful, when using spin-orbit coupling: energy differences are tiny, k-point convergence is tedious and slow, and the computer time you require might be infinite.

Karsai: /* References */

2022-04-08T14:42:21Z

References

← Older revision		Revision as of 14:42, 8 April 2022
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	----		----

	[[Category:INCAR]][[Category:Magnetism]][[Category:Spin-orbit coupling]][[Category:Noncollinear magnetism]]		[[Category:INCAR tag]][[Category:Magnetism]][[Category:Spin-orbit coupling]][[Category:Noncollinear magnetism]]

Karsai: /* Related Tags and Sections */

2022-04-08T14:42:15Z

Related Tags and Sections

← Older revision		Revision as of 14:42, 8 April 2022
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	for the angular momentum <math>l</math>.		for the angular momentum <math>l</math>.

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|MAGMOM}},		{{TAG\|MAGMOM}},
	{{TAG\|SAXIS}},		{{TAG\|SAXIS}},

Vaspmaster: /* Assumptions and output */

2020-11-12T19:18:26Z

Assumptions and output

← Older revision		Revision as of 19:18, 12 November 2020
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	<math>		<math>
	E_{soc}^{ij} = \delta_{{\bf R}_i{\bf R}_j}\delta_{l_il_j} \sum_{\alpha\beta}\langle \phi_i \| H^{\alpha\beta}_{soc} \| \phi_j \rangle		E_{soc}^{ij} = \delta_{{\bf R}_i{\bf R}_j}\delta_{l_il_j} \sum_{n \bf k} w_{\bf k} f_{n\bf k} \sum_{\alpha\beta} \langle \tilde{\psi}^\alpha_{n\bf k} \|\tilde{p}_i \rangle \langle \phi_i \| H^{\alpha\beta}_{soc} \| \phi_j \rangle \langle \tilde{p}_j \| \tilde{\psi}^\beta_{n\bf k} \rangle
	</math>		</math>

	where <math> \phi_i({\bf r}) = R_i(\|{\bf r}-{\bf R}_i\|) Y_{l_im_i}(\hat{ \bf r-\bf R}_i) </math> are the partial waves of an atom centered at <math>{\bf R}_i</math>.{{cite\|Steiner:2016}}		where <math> \phi_i({\bf r}) = R_i(\|{\bf r}-{\bf R}_i\|) Y_{l_im_i}(\hat{ \bf r-\bf R}_i) </math> are the partial waves of an atom centered at <math>{\bf R}_i</math>, <math>\tilde{\psi}^\alpha_{n\bf k}</math> is the spinor-component α of the pseudo-orbital with band-index ''n'' and Bloch-vector '''k''', and <math>f_{n\bf k}</math> and <math>w_{\bf k}</math> are the Fermi- and '''k'''-point weights, respectively.{{cite\|Steiner:2016}}

	After a successful calculation with inclusion of spin-orbit coupling, VASP writes following results to the {{TAG\|OUTCAR}}:		After a successful calculation with inclusion of spin-orbit coupling, VASP writes following results to the {{TAG\|OUTCAR}}:

Kaltakm: /* Assumptions and output */

2019-08-23T11:41:59Z

Assumptions and output

← Older revision		Revision as of 11:41, 23 August 2019
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	-0.0000000 -0.0000000 0.0000000 0.0000000 0.0000000 -0.0000000 0.0000000		-0.0000000 -0.0000000 0.0000000 0.0000000 0.0000000 -0.0000000 0.0000000
	Here "E_soc" represents the accumulated energy <math>E_{soc}=\sum_{ij} E_{soc}^{ij}</math> contribution inside the augmentation sphere that is centered at <math>{\bf R}_1</math> (position of ion 1), while the following entries correspond to the matrix elements		Here "E_soc" represents the accumulated energy <math>E_{soc}=\sum_{ij} E_{soc}^{ij}</math> contribution inside the augmentation sphere that is centered at <math>{\bf R}_1</math> (position of ion 1), while the following entries correspond to the matrix elements
	<math>		<math>E_{soc}^{ij}</math>
	~~\sum_~~{~~\alpha\beta}\langle \phi_{{\bf R~~}~~_1,l,m_i} \| H~~^{~~\alpha\beta}_{soc} \| \phi_{{\bf R}_1,l,m_i~~} ~~\rangle~~
	</math>
	for the angular momentum <math>l</math>.		for the angular momentum <math>l</math>.

Kaltakm: /* Assumptions and output */

2019-08-23T11:41:22Z

Assumptions and output

← Older revision		Revision as of 11:41, 23 August 2019
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	\sum_{\alpha\beta}\langle \phi_{{\bf R}_1,l,m_i} \| H^{\alpha\beta}_{soc} \| \phi_{{\bf R}_1,l,m_i} \rangle		\sum_{\alpha\beta}\langle \phi_{{\bf R}_1,l,m_i} \| H^{\alpha\beta}_{soc} \| \phi_{{\bf R}_1,l,m_i} \rangle
	</math>		</math>
	for the angular momentum <math>l</math>.		for the angular momentum <math>l</math>.

	== Related Tags and Sections ==		== Related Tags and Sections ==

Kaltakm: /* Assumptions and output */

2019-08-23T11:41:05Z

Assumptions and output

← Older revision		Revision as of 11:41, 23 August 2019
Line 132:		Line 132:
	-0.0000000 -0.0000000 -0.0000000 0.0000000 -0.0000000 0.0000000 -0.0000000		-0.0000000 -0.0000000 -0.0000000 0.0000000 -0.0000000 0.0000000 -0.0000000
	-0.0000000 -0.0000000 0.0000000 0.0000000 0.0000000 -0.0000000 0.0000000		-0.0000000 -0.0000000 0.0000000 0.0000000 0.0000000 -0.0000000 0.0000000
	Here "E_soc" represents the accumulated energy <math>E_{soc}=\sum_{ij} E_{soc}^{ij}</math> contribution inside the augmentation sphere that is centered at <math>{\bf R}_1</math> (position of ion 1), while the following entries correspond to the matrix elements <math>E_{soc}^{m_i~~,m_j~~}</math> ~~of different~~ angular momentum <math>l</math>.		Here "E_soc" represents the accumulated energy <math>E_{soc}=\sum_{ij} E_{soc}^{ij}</math> contribution inside the augmentation sphere that is centered at <math>{\bf R}_1</math> (position of ion 1), while the following entries correspond to the matrix elements
			<math>
			\sum_{\alpha\beta}\langle \phi_{{\bf R}_1,l,m_i} \| H^{\alpha\beta}_{soc} \| \phi_{{\bf R}_1,l,m_i} \rangle
			</math>
			for the angular momentum <math>l</math>.

	== Related Tags and Sections ==		== Related Tags and Sections ==