We demonstrate that elastic anomalies and lattice instabilities in the the A15 compounds are describable in terms of first-principles LDA electronic structure calculations. We show that at T=0 V_3Si, V_3Ge, and Nb_3Sn are intrinsically unstable against shears with elastic moduli C_11-C_12 and C_44, and that the zone center phonons, Gamma_2 and Gamma_12, are either unstable or extremely soft. We demonstrate that sublattice relaxation (internal strain) effects are key to understanding the behavior of the A15 materials.
@article{arxiv.cond-mat/9704251,
title = {Anharmonic effects in the A15 compounds induced by sublattice distortions},
author = {Z. W. Lu and B. M. Klein},
journal= {arXiv preprint arXiv:cond-mat/9704251},
year = {2009}
}
Comments
5 pages, RevTex, 3 postscript figures, Submitted to Phys. Rev. Lett. Apr. 23, 1997 July 7, 1997: minor corrections, final accepted version