High pressure, mechanical, and optical properties of ZrW<subscript>2</subscript>O<subscript>8</subscript>.

In this paper, we present the high pressure studies of well known negative thermal expansion material ZrW2O8 on the basis of our density functional theory calculations. We reproduce the experimental α and γ crystal structures of ZrW2O8. We calculate the transition pressure (from α to γ) of this material to be ≈26 kbar. Our calculated positional and axial parameters are in an excellent agreement with the available experimental values for the both α and γ phases of this material. Then we study the mechanical properties of this material. We calculate the elastic constants, bulk, shear and Young's moduli, Poisson's ratio, and Debye temperature of α-ZrW2O8. In our study, we find that the generalized gradient approximation method fails to obtain the correct values while the local density approximation (LDA) method successfully reproduces the experimental bulk modulus of ZrW2O8. Our calculated values of the shear and Young's moduli, Poisson's ratio, and Debye temperature of α-ZrW2O8 with LDA method are also in good agreement with the experimental results. Finally, we predict and analyze the optical properties of this material. [ABSTRACT FROM AUTHOR]