Fermi surface of aluminium under homogeneous strain

A theoretical study of the Fermi surface on aluminium and its strain dependence, based on a local pseudopotential model is presented. New values for the relevant pseudopotential matrix elements in the absence of strain obtained from a fit to recent high precision de Haas-van Alphen measurements are given for different sizes ((4*4), (8*8), (16*16)) of the secular matrix. The Fermi energy and its derivatives are computed by summing over occupied states. The strains are separated into volume-conserving shears (tetragonal or angular) and volume changes. Eight orthogonalised plane waves (OPWS) are required in the secular matrix in order to describe the effect of a general homogeneous deformation on the Fermi surface. The strain response of ten carefully extremalised orbits has been calculated, with the slopes of the form factor at the first two reciprocal lattice vectors as only free parameters.