PRESSURE-INDUCED CHARGE-TRANSFER IN LI AND AL-ALLOYS

In pure metals, the s,p,d,... bands have different energy shifts as th e metals are compressed. Changes that are produced in this way in the amount of s,p,d,... type valence charge affect, e.g., the bonding prop erties of the atoms, which in turn can lead to structural phase transi tions at high pressures. In alloys, the band shifts can produce comple x changes in the electronic structure. The present work deals with the pressure-induced charge transfer in alloys. In Li-X alloys (X=Be,Na,M g,Al,Si,P,Ca,Sr) the number of Li valence electrons is found to increa se along with increasing pressure. This is attributed to the propertie s of Li p states. A similar type of charge transfer is also found in A l-X alloys (X=Ti,Zr,Hf,Cu,Ag,Au), The effects of fully occupied and pa rtially occupied d bands can be studied by considering Al alloyed with noble metals and transition metals. The electronic structure of the a lloys is calculated with the linear muffin-tin orbital atomic sphere a pproximation method. To check the magnitude of the possible computatio nal errors involved in our results we also performed pseudopotential p lane-wave calculations for Li-Mg alloys.