  The pressure dependence of electronic structure, exchange interactions and
Curie temperature in ferromagnetic Heusler alloy Ni2MnSn has been studied
theoretically within the framework of the density-functional theory. The
calculation of the exchange parameters is based on the frozen--magnon approach.
The Curie temperature, Tc, is calculated within the mean-field approximation by
solving the matrix equation for a multi-sublattice system. In agrement with
experiment the Curie temperature increased from 362K at ambient pressure to 396
at 12 GPa. Extending the variation of the lattice parameter beyond the range
studied experimentally we obtained non-monotonous pressure dependence of the
Curie temperature and metamagnetic transition. We relate the theoretical
dependence of Tc on the lattice constant to the corresponding dependence
predicted by the empirical interaction curve. The Mn-Ni atomic interchange
observed experimentally is simulated to study its influence on the Curie
temperature.
