  We have explored the mechanical, electronic, optical and thermoelectric
properties of p-type half-Heusler compound BaAgP for the first time using
density functional theory based calculations. The mechanical and dynamical
stability of this compound is confirmed by studying the Born stability criteria
and phonon dispersion curve, respectively. It is soft, ductile and elastically
anisotropic. The atomic bonding along a-axis is stronger than that along
c-axis. The calculated electronic structure reveals that the studied compound
is an indirect band gap semiconductor. The analysis of charge density
distribution map and Mulliken population reveals that the bonding in BaAgP is a
mixture of covalent and ionic. The optical features confirm that BaAgP is
optically anisotropic. The high absorption coefficient and low reflectivity in
the visible to ultraviolet region make this compound a possible candidate for
solar cell and optoelectronic device applications. The thermoelectric
properties have been evaluated by solving the Boltzmann semi-classical
transport equations. The calculated power factor at 1000K along a-axis is 35.2
micro-W/cmK2 (with tau=10-14 s) which is ~3.5 times larger than that of SnSe, a
promising layered thermoelectric materials. The thermoelectric figure of merit,
ZT of BaAgP is 0.44 which is small due to high thermal conductivity. So the
reduction of thermal conductivity is essential to enhance thermoelectric
performance of BaAgP in device applications.
