  The continuous displacement cluster variation method (CDCVM) has introduced
local atomic displacements into the theoretical framework of the cluster
variation method (CVM) by viewing an atom displaced from a Bravais lattice
point as a particular atomic species located at the lattice point. This idea of
conversion from a freedom of local displacements into configurational freedom
is extended in this paper to magnetic freedoms. Various magnitudes of local
magnetic moments are considered, as well as two spin directions, on up-spins
and down-spins. The approach is applied to pure Ni and its Curie temperature is
explored with the entropy formula of the tetrahedron approximation in the CVM,
using the first-nearest-neighbor pair interaction energies extracted from the
total energies of various spin configurations, which are estimated from
electronic-structure calculations.
