The Structural, Lattice Dynamic, Thermodynamic, and Mechanical Characterization of Na ₂ Mo ₂ O ₇ Crystal by First‐Principles

The structural, electronic, lattice dynamic, thermodynamic, and mechanical properties of disodium dimolybdate (Na2Mo2O7) are studied using first-principles. First, for the crystal structure, the calculated structural parameters have a standard deviation of less than 1.7% compared with the experimental results. Then, the calculated electronic energy band and density of states reveal that Na2Mo2O7 is an insulator and its bandgap is about 2.87 eV. In addition, the linear response method is used to study the lattice dynamics, and the complete phonon dispersion curve, infrared spectra, Raman shift, Born effective charge, and longitudinal optical–transverse optical (LO–TO) splitting characteristic for Na2Mo2O7 are presented for the first time; its thermodynamic properties are worked out based on the phonon density of states (PDOS). Furthermore, the result of elastic anisotropy shows the title compound is a highly anisotropic material. The calculation results in this article are conducive to the development of Na2Mo2O7 and provide guidelines for further experimental research to a certain extent.