CALCULATION OF BULK PROPERTIES OF METALS USING STRUCTURELESS PSEUDOPOTENTIAL FORMALISM

Abstract

Valency, electron density parameter and the Ashcroft core radius which arc characteristics of structureless pseudopotential model are used to calculate the binding energy, the bulk modulus, the effective potential and the screened effective potential of some metals. The calculated values of the binding energy and the bulk modulus were compared with the available experimental values. Results show that the binding energy and bulk modulus calculated using the structurclcss pscudopotcntial model were in good agreement with experimental values unlike the calculated values using the jellium model. The binding energy calculated using the structureless pseudopotential model increases with an increase in electron density parameter while the calculated values ofthe .bindi ng energy usi ng the jell iUI11 model decreases with increase in electron density parameter. But the degree of agreement with experimental values was found to decrease with an increase in the valence of the metals. The calculated bulk modulus at the low density limit were in very good agreement with experimental values and 'at high density limit where we have the transition and noble metals, the agreement decreases. The effective potential and the screened effective potentials depend on the distance, valency, the Ashcroft core radius and the electron gas parameter of the metal. The obtained effective potential was screened using the improved Hartree dielectric function. The obtained values of effective and screened effective potentials based on the structure less pseudopotential model vary in the same way with distance. The magnitude of the potentials at a point depends on the valences of the metal. A range of distance of -5 to 6A 0 was used and the calculated effective potential and screened effective potential of the metals are mostly auractivc except within -1.5 to - 0.75Ao where it is repulsive Corthe metals. Also a study olthc variation ofthe effective potential at a point with electron density parameter revealed that the potential of the metals in the high density limit is weaker than those in the low-density limit.