Vikas Nayak

Should muffin tin radius vary in different structures of a material?: A case study

Quantum mechanical calculations based on density functional theory and a generalized gradient approximation (GGA) have been used to study the structural properties of YbN. Its predicted unit cell lattice parameter in NaCl (B1) structure is 4.7810A and in CsCl (B2) structure it is 2.8685A. In the determination of lattice parameter the muffin tin radius (RMT) of constituent atoms play important role. In both the structures the muffin tin radius for Yb and N converges to 2.3 and 1.4 a.u., respectively.

A first-principle approach to study the structural and elastic properties of alkali hydrides

The comparative study of structural stability and elastic constants of alkali hydrides (LiH, NaH, KH) and their extra added hydrogen compounds (LiH+2H, NaH+2H and KH+2H) in NaCl structure has been presented. Calculations have been performed using first-principles approach and employing full potential linearized augmented plane wave (FP-LAPW) method. Generalized gradient approximation (GGA) has been used for solving exchange correlation functional. Our obtained elastic constants of LiH, NaH and KH are in good agreement with reported experimental and other theoretical data.

Hydrogen storage in LiH: A first principle study

First principles calculations have been performed on the Lithium hydride (LiH) using the full potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory. We have extended our calculations for LiH+2H and LiH+6H in NaCl structure. The structural stability of three compounds have been studied. It is found that LiH with 6 added Hydrogen atoms is most stable. The obtained results for LiH are in good agreement with reported experimental data. Electronic structures of three compounds are also studied. Out of three the energy band gap in LiH is ∼3.0 eV and LiH+2H and LiH+6H are metallic.

Study of Structural and Electronic Behavior of BeH2 as Hydrogen Storage Compound: An Ab Initio Approach

The quantum mechanical calculations based on density functional theory (DFT) have been performed to study ground state structural and electronic properties of BeH2 and along with doping of two (BeH2

A first-principle approach to study the thermodynamical behavior of MgH2+nH (n=0, 4, 8)

The nature of material at high temperature and pressure is of immense interest for both theory and experimental point of view. For this, the behavior of thermal parameters such as bulk modulus and thermal expansion coefficients as a function of high temperature and high pressure have been studied by using quasi harmonic Debye model as implemented on GIBBS package. The obtained plots are presented and discussed in the paper. We expect that the obtained results will be very useful for experimental research in the search for new hydrogen storage materials

Cohesive energy of KH+nH (n=0, 2, 6, 8): A DFT study

The first-principle calculations based on density functional theory (DFT) have been carried out to calculate the cohesive energy of potassium hydride (KH+nH; n=0, 2, 6, 8). The generalized gradient approximation (GGA) has been employed to calculate the exchange correlation functional, based on full potential linearized augmented plane wave (FP-LAPW) method. The equilibrium lattice constant, bulk modulus and cohesive energy of KH and their added hydrogen compounds have been reported. The obtained cohesive energies are 5.427eV, 6.447eV, 8.679 eV and 16.4 eV for KH+nH; (n=0, 2, 6, 8).

Phase transition and optoelectronic properties of MgH2

In this article, structural and electronic properties of MgH2 have been studied. The aim behind this study was to find out the ground state crystal structure of MgH2. For the purpose, density functional theory (DFT)-based full-potential linearized augmented plane wave (FP-LAPW) calculations have been performed in three different space groups: P42/mnm (α-MgH2), Pa3 (β-MgH2) and Pbcn (γ-MgH2). It has been found that the ground state structure of MgH2 is α-MgH2. The present study shows that α-MgH2 transforms into γ-MgH2 at a pressure of 0.41 GPa. After further increase in pressure, γ-MgH2 transforms into β-MgH2 at a pressure of 3.67 GPa. The obtained results are in good agreement with previously reported experimental data. In all the studied phases, the behavior of MgH2 is insulating and its optical conductivity is around 6.0 eV. The α-MgH2 and γ-MgH2 are anisotropic materials while β-MgH2 is isotropic in nature.