Structural properties and mechanical stability of monoclinic lithium disilicate

The structural, electronic and mechanical properties of monoclinic Li₂Si₂O₅ are explored using density functional theory. Different exchange-correlation functionals are considered and the results are correlated to experimental data. The calculated electronic band structure and density of states indicate that monoclinic Li₂Si₂O₅ has an insulating character with an indirect band gap of 4.98eV. Elastic stiffness coefficients and the bulk, shear and Young's moduli are also calculated. Our calculations predict that Li₂Si₂O₅ is a ductile compound. We show that monoclinic Li₂Si₂O₅ behaves as a specially orthotropic material, meaning that the structure can be masked by the orthorhombic form.