137
With the rapid development of advanced technologies,
the demands for the design of components and the
production of new materials which are strong, stiff and
ductile are increasing. Stable materials responding these
requirements are the inter-metallic compounds (Kart et
al. 2008). They have structural properties which differ
greatly from constituent metals. Cu-based inter-metallics
have motivated the strong interest in their fundamental
properties as they have received considerable attention
due to their promising use as catalysts in many
technologically important areas and future technology.
MATERIALS AND METHODS
All the systems considered are studied using Tight
Binding Linear Muffin-Tin Orbitals Atomic Sphere
Approximation (TB-LMTO-ASA). All results are derived
from self-consistent calculations based on density-
functional theory in the local-density approximation
(LDA) (Hohenberg & Kohn, 1964). Throughout the
calculation we use the exchange-correlation potential
of von Barth and Hedin (Barth & Hedin, 1972). The
crystal potential is constructed of over-lapping Wigner-
Seitz spheres for each atom in the unit cell. According to
the spirit of the tight-binding Linear muffin-tin Orbital
method with atomic sphere approximation (TB-LMTO-
ASA) procedure, only the energetically higher-lying
valence states have been included in the self-consistent
calculations of the effective crystal potentiall (Skriver,
1984; Aschroft & Mermin, 1976; Mizutani, 2001). The
deeper lying core states are treated as atomic like in the
inner states, so called frozen core approximation. The
calculations were iterated to self-consistency with an
error in total energy less that 10
-6
Rydberg.
INTRODUCTION
The main basis for understanding materials ultimately rests
upon understanding their electronic structure (Martin,
2004). The cohesive, electronic, optical, magnetic and
super-conducting properties of solids are dominated by
the behavior of valence electrons moving in the field
of the ion-core of constituent atoms. The development
of electronic structure calculations has taken place in
several steps. The Tight-Binding Linear Muffin-Tin
Orbital method with Atomic Sphere Approximation (TB-
LMTO-ASA) (Skriver, 1984; Andersen, 1975; Andersen
et al., 1984) is one of the frequently used technique to
deal with the electronic properties; especially band
structure and density of states of the solids (Kaphle et
al. 2012, Andersen, 1984; Ganguly et al. 2011 ). In the
present work we have used TB-LMTO-ASA method to
study the electronic and magnetic properties of different
alloys of Copper (Cu), Palladium (Pd) and Platinum (Pt)
i.e., CuPd, CuPt, Cu
3
Pd & Cu
3
Pt. The homogeneous
mixture of two or more metals or of metallic elements
with non metallic elements is called alloy.
If there is a mixture of only two types of atoms, it is
called binary alloy. Binary alloys may be ordered or
disordered depending upon atomic positions (Ashcroft
& Mermin, 1976; Kittel, 1966). If the atoms are situated
by making symmetry in the crystals then they are called
ordered alloys and if the atoms are situated randomly in
the crystals so that they fail to have crystal symmetry
then they are called disordered alloys. Metals and alloys
are materials of great scientific as well as practical
importance.
Study of Electronic and Magnetic Properties of CuPd, CuPt, Cu
3
Pd and
Cu
3
Pt: Tight Binding Linear Muffin-Tin Orbitals Approach
Shiva Dahal, Gyanu Kafle, Gopi Chandra Kaphle and Narayan Prasad Adhikari*
Central Department of Physics
Tribhuvan University, Kirtipur, Kathmandu, Nepal
*Email:npadhikri@tucdp.edu.np; npadhikari@gmail.com
ABSTRACT
Electronic structure of ordered alloys CuPd, CuPt, Cu
3
Pd and Cu
3
Pt have been studied using Tight Binding Linear
Muffin-Tin Orbitals Atomic Sphere Approximation (TB-LMTO-ASA). For the electronic properties, we have performed
band structure calculations. Our findings show that all the systems considered are metallic in nature. To know the
contribution of the orbitals in the bands, the system is analyzed via fat bands which reveal most of the contributions on
valence band for CuPd, CuPt, Cu
3
Pd and Cu
3
Pt is from d-orbital and on conduction band is from s and p-orbitals. We
have also checked the magnetic properties of the alloys. The density of states for spin up and spin down electrons have
found to be same in each and every steps, showing non-magnetic nature of CuPd, CuPt, Cu
3
Pd and Cu
3
Pt.
Key words: Band structure, TB-LMTO-ASA, Alloys, Density functional theory
Journal of Institute of Science and Technology, 2014, 19(1): 137-144, © Institute of Science and Technology, T.U.