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LAPWSO (adds spin orbit coupling)

lapwso includes spin-orbit (SO) coupling in a second-variational procedure and computes eigenvalues and eigenvectors (stored in case.vector) using the scalar-relativistic wavefunctions from lapw1. For reference see Singh 94 and Novak 97. The SO coupling must be small, as it is diagonalized in the space of the scalar relativistic eigenstates. For large spin orbit effects it might be necessary to include many more eigenstates from lapw1 by increasing EMAX in case.in1 (up to 10 Ry!). It is considered only within the atomic spheres and thus the results may depend to some extent on atomic spheres radii. The nonspherical potential is neglected when calculating $dV\over{dr}$.

In spin-polarized calculations the presence of spin-orbit coupling can split equivalent atoms into non-equivalent ones or at least may lower the symmetry of the system. It is then necessary to consider a larger part of the Brillouin zone and the input for lapw2 should also be modified since the potential has lower symmetry than in the non-relativistic case. The following inputs must be changed:

We recommend to use initso (see Sec.5.2.10) which helps you to setup spinorbit calculations, but in some cases an even more complicated procedure might be necessary.

Note: SO eigenvectors are complex and thus lapw2c must be used in a selfconsistent calculation. Since there are twice as many eigenvalues as in a non-SO calculation the NUME Parameter must be large enough.



 
next up previous contents
Next: Execution Up: Programs for running an Previous: Input

2000-04-11