Relativistic Effects and Spin¶
By default Band calculations are spin-restricted. You can instruct Band to perform a spin-unrestricted via the
Unrestricted [True | False]
Type: Bool Default value: False Description: Controls wheather Band should perform a spin-unrestricted calculation. Spin-unrestricted calculations are computationally roughly twice as expensive as spin-restricted.
The orbitals are occupied according to the aufbau principle.
If you want to enforce a specific spin-polarization (instead of occupying according to the aufbau principle) you can use the
Type: Float Description: Enforce a specific spin-polarization instead of occupying according to the aufbau principle. The spin-polarization is the difference between the number of alpha and beta electron. Thus, a value of 1 means that there is one more alpha electron than beta electrons. The number may be anything, including zero, which may be of interest when searching for a spin-flipped pair, that may otherwise end up in the (more stable) parallel solution.
Relativistic effects are treated with the accurate and efficient ZORA approach [17, 18], controlled by the
Relativistic keyword. Relativistic effects are negligible for light atoms, but grow to dramatic changes for heavy elements. A rule of thumb is: Relativistic effects are quite small for elements of row 4, but very large for row 6 elements (and later).
Relativity Level [None | Scalar | Spin-Orbit] End
Type: Block Description: Options for relativistic effects.
Type: Multiple Choice Default value: None Options: [None, Scalar, Spin-Orbit] Description: None: No relativistic effects. Scalar: Scalar relativistic ZORA. This option comes at very little cost. SpinOrbit: Spin-orbit coupled ZORA. This is the best level of theory, but it is (4-8 times) more expensive than a normal calculation. Spin-orbit effects are generally quite small, unless there are very heavy atoms in your system, especially with p valence electrons (like Pb). See also the SpinOrbitMagnetization key.
See also the SpinOrbitMagnetization key.