Structural, elastic, electronic, thermodynamic, and optical properties of layered BaPd2As2 pnictide superconductor: A first principles investigation

Abstract

BaPd 2 As 2 belongs to 122 pnictide group, famous for exhibiting superconductivity at high temperatures and other electronic correlations. Unlike the 122 iron arsenides, BaPd 2 As 2 exhibits superconductivity at low temperature when realized in theThCr 2 Si 2 type structure (I4/mmm). We have performed density functional theory (DFT) based calculations to investigate the structural, elastic, electronic, thermodynamic, and optical properties of BaPd 2 As 2 in this study. The structural, elastic, and the band structure features are compared with the available experimental and theoretical results. Pressure and temperature dependences of various important thermodynamic functions, e.g., bulk modulus, specific heats at constant pressure and volume, coefficient of volume thermal expansion, and Debye temperature are studied in details for the first time. The optical parameters of BaPd 2 As 2 are also studied in details for the first time. The optical properties compliment the electronic band structure characteristics. Optical constants show significant dependence of the state of polarization of the incident electric field. BaPd 2 As 2 exhibits high reflectance in the infrared and near-visible region and strongly absorbs the ultraviolet radiation. The relevance of the electronic energy density of states and the characteristic phonon frequency to superconductivity in BaPd 2 As 2 is also discussed.

First Principle Study of the Mechanical Properties and Phonon Dispersion of the Iron Pnictide Compound EuFe2As2

“…The values reported in Table 2 are all positive and satisfy all the above four criteria, hence proving that this tetragonal compound is stable. C 11 > C 33 as seen from Table 2 , implying that the crystal is more stiff along 100 and 010 axes, results which are in agreement with the study on a similar iron pnictide BaPd 2 As 2 [ 25 ]. C 12 – C 44 gives the Cauchy pressure, which, if positive, makes the compound ductile.…”

“…C 12 – C 44 gives the Cauchy pressure, which, if positive, makes the compound ductile. From Table 2 , the Cauchy pressure is positive; hence the material is ductile, a result similar to that of a related iron pnictide [ 25 ].…”

Structural and electronic properties of the iron pnictide compound EuFe2As2 from first principles

“…The mechanical properties we obtained from the computation are summarized in Table 1 below. The Poisson's ratio was found to be ∼0.32 at absolute zero temperature, our result compared well to a value of 0.302 for other families of Pnictides [41], the difference may be as a result of varying atoms present in the two compounds and a slight difference in the crystal structure. This value further confirmed that EuFe 2 As 2 is a stable and metallic [45, ] Other Pnictides such as SrFe 2 As 2 have a Poisson's ratio of ∼0.48 upon application of pressure [47], which causes the lattice parameters to change.…”

“…Other minor curves are left out in the illustration since their contribution to the Partial Density of States was minimal. The density of states of other Pnictides shows similar gaps [41].…”

Structural, elastic, electronic, andoptical properties of layered TiNX (X = F, Cl, Br, I) compounds: a density functional theory study

“…This reflects strongly the layered structural and bonding features of TiNX. The machinability index of TiNX compares favorably to that for other layered ternaries [14,16,17].…”