L. Nordstrom et al., Spin-orbit coupling in the actinide elements: A critical evaluation of theoretical equilibrium volumes - art. no. 035103, PHYS REV B, 6303(3), 2001, pp. 5103
The difficulty of converging the contribution of the spin-orbit interaction
to the total energy within an ls basis in actinide electronic structure ca
lculations is discussed in detail. In particular, it is demonstrated that t
he source of the poor convergence is the treatment of the actinide 6p state
s. The limitation of the standard approach to relativity in full potential
methods is manifested in muffin-tin based methods by a dependence of the to
tal energy on the choice of muffin-tin radius. Despite this limitation it i
s found that structural phase stabilities are not affected, nor are pressur
e induced phase transitions. In order to treat the relativistic spin-orbit
coupling in as large a part of space as possible one should, in muffin-tin
based calculations, use a radius that is touching, or near touching, for al
l calculated volumes.