Category:Spin-orbit coupling - Revision history

Csheldon at 11:59, 16 June 2026

2026-06-16T11:59:03Z

← Older revision		Revision as of 11:59, 16 June 2026
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	Spin-orbit coupling splits bands that would otherwise be degenerate and gives each Bloch state a spin expectation value that varies across the Brillouin zone, the spin texture seen in Rashba and topological systems. After a [[Setting up an electronic minimization\|self-consistent calculation]] with spin-orbit coupling, the spin-resolved band structure is obtained from a non-self-consistent run along a '''k'''-point path, and the site- and orbital-projected spin components are written with the projection tag ({{TAG\|LORBIT}}). A step-by-step workflow for computing and visualizing the spin texture is given in the how-to [[Computing the spin texture]].		Spin-orbit coupling splits bands that would otherwise be degenerate and gives each Bloch state a spin expectation value that varies across the Brillouin zone, the spin texture seen in Rashba and topological systems. After a [[Setting up an electronic minimization\|self-consistent calculation]] with spin-orbit coupling, the spin-resolved band structure is obtained from a non-self-consistent run along a '''k'''-point path, and the site- and orbital-projected spin components are written with the projection tag ({{TAG\|LORBIT}}). A step-by-step workflow for computing and visualizing the spin texture is given in the how-to [[Computing the spin texture]].

			== Tutorials ==
			*{{Tutorial\|magnetism:e06\|Spin-orbit coupling for bcc Fe bulk.}}

Huebsch: /* Spin-quantization axis and magnetic energy landscape */

2026-06-16T09:45:41Z

Spin-quantization axis and magnetic energy landscape

← Older revision		Revision as of 09:45, 16 June 2026
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	Even when you are not after a property that intrinsically requires spin-orbit coupling, it can still change your results. For heavy elements the effect on total energies, equilibrium geometries, and band energies may be far from negligible. Rather than assuming the interaction can be ignored, test its influence explicitly: run the property of interest once without and once with spin-orbit coupling and compare. If the difference is within your target accuracy, you may safely neglect it for that system; if not, keep it switched on. As a rule of thumb, the heavier the elements in your structure, the more likely spin-orbit coupling matters, since the SOC constant $\propto Z^4$.		Even when you are not after a property that intrinsically requires spin-orbit coupling, it can still change your results. For heavy elements the effect on total energies, equilibrium geometries, and band energies may be far from negligible. Rather than assuming the interaction can be ignored, test its influence explicitly: run the property of interest once without and once with spin-orbit coupling and compare. If the difference is within your target accuracy, you may safely neglect it for that system; if not, keep it switched on. As a rule of thumb, the heavier the elements in your structure, the more likely spin-orbit coupling matters, since the SOC constant $\propto Z^4$.

	== ~~Spin-quantization axis and magnetic~~ energy ~~landscape~~ ==		== Magnetic anisotropy energy ==

	With spin-orbit coupling the energy is no longer invariant under a global rotation of the spins, so it depends on the orientation of the spins relative to the crystal axes. The total-energy differences between calculations with different spin-quantization axes ({{TAG\|SAXIS}}) is called magnetic anisotropy energy. In these calculations, the orbital magnetic moments may become nonzero and can be written to the output ({{TAG\|LORBMOM}}). For the details, see [[:Category:Noncollinear magnetism\|Noncollinear magnetism]].		With spin-orbit coupling the energy is no longer invariant under a global rotation of the spins, so it depends on the orientation of the spins relative to the crystal axes. The total-energy differences between calculations with different spin-quantization axes ({{TAG\|SAXIS}}) is called magnetic anisotropy energy. In these calculations, the orbital magnetic moments may become nonzero and can be written to the output ({{TAG\|LORBMOM}}). For the details, see [[:Category:Noncollinear magnetism\|Noncollinear magnetism]].

Huebsch at 09:43, 15 June 2026

2026-06-15T09:43:01Z

← Older revision		Revision as of 09:43, 15 June 2026
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	== Band structure and spin texture ==		== Band structure and spin texture ==

	Spin-orbit coupling splits bands that would otherwise be degenerate and gives each Bloch state a spin expectation value that varies across the Brillouin zone, the spin texture seen in Rashba and topological systems. After a [[Setting up an electronic minimization\|self-consistent calculation]] with spin-orbit coupling, the spin-resolved band structure is obtained from a non-self-consistent run along a '''k'''-point path, and the site- and orbital-projected spin components are written with the projection tag ({{TAG\|LORBIT}}). A step-by-step workflow for computing and visualizing the spin texture is given in the how-to [[~~Construction:~~Computing the spin texture]].		Spin-orbit coupling splits bands that would otherwise be degenerate and gives each Bloch state a spin expectation value that varies across the Brillouin zone, the spin texture seen in Rashba and topological systems. After a [[Setting up an electronic minimization\|self-consistent calculation]] with spin-orbit coupling, the spin-resolved band structure is obtained from a non-self-consistent run along a '''k'''-point path, and the site- and orbital-projected spin components are written with the projection tag ({{TAG\|LORBIT}}). A step-by-step workflow for computing and visualizing the spin texture is given in the how-to [[Computing the spin texture]].

Huebsch at 09:39, 15 June 2026

2026-06-15T09:39:05Z

← Older revision		Revision as of 09:39, 15 June 2026
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	Spin-orbit coupling (SOC) is the relativistic interaction between the spin of an electron and its orbital motion. It is one of the [[relativistic corrections]] that become important for systems containing heavy elements, where it lifts spin degeneracies, splits energy bands, and couples the magnetic moments to the crystal lattice. Capturing this interaction is essential for properties such as magnetic anisotropy, orbital magnetic moments, the Rashba and Dresselhaus effects, and the spin texture of electronic states. In VASP, spin-orbit coupling is treated within the noncollinear framework, so that the wavefunction is described by two-component spinors rather than scalar orbitals.		'''Spin-orbit coupling''' (SOC) is the relativistic interaction between the spin of an electron and its orbital motion. It is one of the '''relativistic corrections''' that become important for systems containing heavy elements, where it lifts spin degeneracies, splits energy bands, and couples the magnetic moments to the crystal lattice. Capturing this interaction is essential for properties such as magnetic anisotropy, orbital magnetic moments, the Rashba and Dresselhaus effects, and the spin texture of electronic states. In VASP, spin-orbit coupling is treated within the noncollinear framework, so that the wavefunction is described by two-component spinors rather than scalar orbitals.

	== Enabling spin-orbit coupling ==		== Enabling spin-orbit coupling ==

	Spin-orbit coupling is switched on with a single tag, which automatically activates the noncollinear framework. It is implemented for the projector-augmented-wave (PAW) method only and must be run with the noncollinear VASP executable <code>vasp_ncl</code>. Because the calculation now uses two-component spinors, the magnetic configuration is specified by three ~~Cartesian~~ components per atom.		Spin-orbit coupling is switched on with a single tag ({{TAG\|LSORBIT}}), which automatically activates the [[:Category:Noncollinear magnetism\|noncollinear framework]] ({{TAG\|LNONCOLLINEAR}}). It is implemented for the projector-augmented-wave (PAW) method only and must be run with the noncollinear VASP executable <code>vasp_ncl</code>. Because the calculation now uses two-component spinors, the magnetic configuration is specified by three components per atom ({{TAG\|MAGMOM}}).

	{{TAG\|~~LSORBIT~~}}~~, {{TAG\|LNONCOLLINEAR}}, [[:Category:Noncollinear magnetism\|Noncollinear magnetism]]~~

	== When to include spin-orbit coupling ==		== When to include spin-orbit coupling ==

	Even when you are not after a property that intrinsically requires spin-orbit coupling, it can still change your results. For heavy elements the effect on total energies, equilibrium geometries, and band energies may be far from negligible. Rather than assuming the interaction can be ignored, test its influence explicitly: run the property of interest once without and once with spin-orbit coupling and compare. If the difference is within your target accuracy, you may safely neglect it for that system; if not, keep it switched on. As a rule of thumb, the heavier the elements in your structure, the more likely spin-orbit coupling matters.		Even when you are not after a property that intrinsically requires spin-orbit coupling, it can still change your results. For heavy elements the effect on total energies, equilibrium geometries, and band energies may be far from negligible. Rather than assuming the interaction can be ignored, test its influence explicitly: run the property of interest once without and once with spin-orbit coupling and compare. If the difference is within your target accuracy, you may safely neglect it for that system; if not, keep it switched on. As a rule of thumb, the heavier the elements in your structure, the more likely spin-orbit coupling matters, since the SOC constant $\propto Z^4$.

	~~{{TAG\|LSORBIT}}~~		== Spin-quantization axis and magnetic energy landscape ==

	~~== Spin-quantization axis and magnetic properties ==~~		With spin-orbit coupling the energy is no longer invariant under a global rotation of the spins, so it depends on the orientation of the spins relative to the crystal axes. The total-energy differences between calculations with different spin-quantization axes ({{TAG\|SAXIS}}) is called magnetic anisotropy energy. In these calculations, the orbital magnetic moments may become nonzero and can be written to the output ({{TAG\|LORBMOM}}). For the details, see [[:Category:Noncollinear magnetism\|Noncollinear magnetism]].

	With spin-orbit coupling the energy is no longer invariant under a global rotation of the spins, so it depends on the orientation of the spins relative to the crystal axes. ~~Total~~-energy differences between calculations with different spin-quantization axes ~~therefore yield the~~ magnetic anisotropy energy, ~~and~~ orbital magnetic moments become nonzero and can be written to the output. Spin-orbit coupling is built on the noncollinear-magnetism machinery and shares its conventions for the spin-quantization axis and the magnetic configuration. For the details, see [[:Category:Noncollinear magnetism\|Noncollinear magnetism]].

	~~{{TAG\|SAXIS}},~~ {{TAG\|LORBMOM}}, [[:Category:Noncollinear magnetism\|Noncollinear magnetism]]

	== Band structure and spin texture ==		== Band structure and spin texture ==

	Spin-orbit coupling splits bands that would otherwise be degenerate and gives each Bloch state a spin expectation value that varies across the Brillouin zone, the spin texture seen in Rashba and topological systems. After a self-consistent calculation with spin-orbit coupling, the spin-resolved band structure is obtained from a non-self-consistent run along a '''k'''-point path, and the site- and orbital-projected spin components are written with the projection tag. A step-by-step workflow for computing and visualizing the spin texture is given in the how-to [[Construction:Computing the spin texture]].		Spin-orbit coupling splits bands that would otherwise be degenerate and gives each Bloch state a spin expectation value that varies across the Brillouin zone, the spin texture seen in Rashba and topological systems. After a [[Setting up an electronic minimization\|self-consistent calculation]] with spin-orbit coupling, the spin-resolved band structure is obtained from a non-self-consistent run along a '''k'''-point path, and the site- and orbital-projected spin components are written with the projection tag ({{TAG\|LORBIT}}). A step-by-step workflow for computing and visualizing the spin texture is given in the how-to [[Construction:Computing the spin texture]].

	~~{{TAG\|LORBIT}}~~

	~~[[Category:VASP\|Spin-orbit coupling]][[Category:Magnetism]]~~

Schlipf: Expand category page: intro, enabling SOC, when to include SOC, spin-quantization axis and magnetic properties, band structure and spin texture; cross-link noncollinear magnetism

2026-06-10T11:43:19Z

Expand category page: intro, enabling SOC, when to include SOC, spin-quantization axis and magnetic properties, band structure and spin texture; cross-link noncollinear magnetism

@@ Line 1: / Line 1: @@
-== Theory ==
+Spin-orbit coupling (SOC) is the relativistic interaction between the spin of an electron and its orbital motion. It is one of the [[relativistic corrections]] that become important for systems containing heavy elements, where it lifts spin degeneracies, splits energy bands, and couples the magnetic moments to the crystal lattice. Capturing this interaction is essential for properties such as magnetic anisotropy, orbital magnetic moments, the Rashba and Dresselhaus effects, and the spin texture of electronic states. In VASP, spin-orbit coupling is treated within the noncollinear framework, so that the wavefunction is described by two-component spinors rather than scalar orbitals.
-*Spin-orbit coupling: {{TAG|LSORBIT}}.
-== How to ==
+== Enabling spin-orbit coupling ==
-*Spin-orbit coupling: {{TAG|LSORBIT}}.
-----
+Spin-orbit coupling is switched on with a single tag, which automatically activates the noncollinear framework. It is implemented for the projector-augmented-wave (PAW) method only and must be run with the noncollinear VASP executable <code>vasp_ncl</code>. Because the calculation now uses two-component spinors, the magnetic configuration is specified by three Cartesian components per atom.
 [[Category:VASP|Spin-orbit coupling]][[Category:Magnetism]]

Karsai at 15:41, 11 March 2019

2019-03-11T15:41:03Z

← Older revision		Revision as of 15:41, 11 March 2019
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	== Theory ==		== Theory ==
			*Spin-orbit coupling: {{TAG\|LSORBIT}}.
	== How to ==		== How to ==
			*Spin-orbit coupling: {{TAG\|LSORBIT}}.
	----		----

	[[Category:VASP\|Spin-orbit coupling]][[Category:Magnetism]]		[[Category:VASP\|Spin-orbit coupling]][[Category:Magnetism]]

Karsai: Created page with "== Theory == == How to == ---- Spin-orbit couplingCategory:Magnetism"

2019-03-11T15:29:14Z

Created page with "== Theory == == How to == ---- Spin-orbit coupling Category:Magnetism"

New page

== Theory ==

== How to ==
----

[[Category:VASP|Spin-orbit coupling]][[Category:Magnetism]]