Electric field gradients and band structure for V3Si

The electric field gradient (e.f.g.) tensor measured for V3Si is analysed in terms of the electronic band structure. This crystal undergoes a martensitic transformation at Tsub(m) = 21.30K. Above Tsub(m) the crystal is cubic and the point symmetry of the vanadium atoms is tetragonal. Below Tsub(m) the crystal becomes tetragonal and nuclei which sit on chains orthogonal to the axis of symmetry 'see' orthorhombic neighbourhood. The experimental data include: (i) the value of the axial part of the e.f.g. (q) measured in the cubic phase; (ii) the asymmetry part of the e.f.g. tensor measured in a single crystal below Tsub(m); (iii) the difference of q measured for orthogonal chains in the tetragonal phase. All this data could not be explained by the well-known model of Watson, Gossard and Yefet (Phys. Rev.;140:A375(1965)). Here a full analysis is given, in terms of an approximate LCAO band structure calculation. It is found that assuming the inaccuracies of the calculated band structure are at most 50 m Ry, the peak in the density of states which 'falls' on Esub(F) is X3(delta2 + π). In this case all the experimental data may be explained to within an accuracy of a factor of 2 to 3. (author)