Study of electronic structure and Compton profiles of transition metal diborides

• Samir Bhatt^a, 
• N.L. Heda^b, 
• Kishor Kumar^a, 
• B.L. Ahuja^a, , 

• ^a Department of Physics, ML Sukhadia University, Udaipur 313001, Rajasthan, India
• ^b Department of Pure and Applied Physics, University of Kota, Kota 324007, Rajasthan, India

Received 21 February 2017, Revised 6 May 2017, Accepted 8 May 2017, Available online 9 May 2017

Abstract

We report Compton profiles (CPs) of transition metal diborides (MB₂; M= Ti and Zr) using a 740 GBq ¹³⁷Cs Compton spectrometer measured at an intermediate resolution of 0.34 a.u. To validate the experimental momentum densities, we have employed the linear combination of atomic orbitals (LCAO) method to compute the theoretical CPs along with the energy bands, density of states (DOS) and Mulliken's population response. The LCAO computations have been performed in the frame work of density functional theory (DFT) and hybridization of Hartree-Fock and DFT (namely B3LYP and PBE0). For both the diborides, the CPs based on revised Perdew-Burke-Ernzerhof exchange and correlation functions (DFT-PBESol) lead to a better agreement with the experimental momentum densities than other reported approximations. Energy bands, DOS and real space analysis of CPs confirm a metallic-like character of both the borides. Further, a comparison of DFT-PBESol and experimental data on equal-valence-electron-density scale shows more ionicity in ZrB₂ than that in TiB₂, which is also supported by the Mulliken's population based charge transfer data.

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