  The self-diffusion coefficient of crystalline solids as a function of density
and temperature may derive from thermodynamics concepts and an earlier elastic
thermodynamic point defect model [P. Varotsos and K. Alexopoulos, Phys. Rev. B
15, 4111 (1977); Phys. Rev. B 18, 2683 (1978)]. Compensation laws ruling
self-diffusion parameters in carbon-subgroup crystals obtained from theoretical
calculations are predicted, as well.
