Prediction of New Hydrogen Storage Materials: Structural Stability of SrAlH3 from First Principle Calculation

The structural stability of the SrAlH3 has been investigated using the density-functional theory with the generalized-gradient approximation, pseudo-potential and plane wave method, for hydrogen storage application. Indeed, we have predicted structures for hypothetical compounds SrAlH3 by considering 24 different guess structures possible and have been attained through energy minimization and force relaxation, for the above guess structures. The most stable arrangement being the tetragonal PCF3-type (tP40) structure, which contains distorted octahedral. At higher pressure this phase transform into the orthorhombic GdFeO3-type (oP20) at 31.8 GPa. We have fitted the total energy as function of cell volume using the so-called universal equation of state and we have found that SrAlH3 have a bulk modulus B equal to 37.11 and 44.88 Gpa for P42/nmc (space group n° 137) and Pnma (space group 62) respectively. The formation energy, the electronic density of states, charge density, charge transfer, electron-localization function and Born effective charge are investigated and discussed.