Effects of Finite-Temperature Force Constants on Lattice Thermal Conductivity of Mgo Under High Pressure and High Temperature

Abstract

The lattice thermal conductivity ([Formula: see text] of mantle minerals critically influences Earth’s convective dynamics and heat transport. Combining first-principles calculations with anharmonic lattice dynamics, we systematically investigate [Formula: see text] of MgO at 0[Formula: see text]GPa and 135[Formula: see text]GPa, employing finite-temperature Force Constants (FCs) to analyze temperature effects on [Formula: see text]. Results demonstrate that finite-temperature FCs yield significantly reduced [Formula: see text] compared to zero-temperature FCs: a 4.88% reduction at 0[Formula: see text]GPa (300[Formula: see text]K FCs) ensures agreement with experimental data. At 135[Formula: see text]GPa, this discrepancy intensifies, with a 23% decrease in [Formula: see text] between 4000[Formula: see text]K FCs and zero-temperature FCs. This reduction stems from enhanced anharmonic scattering rates and diminished group velocities within the 100–150 rad/ps range. Crucially, the [Formula: see text] decline at 135[Formula: see text]GPa (4000[Formula: see text]K FCs) directly reduces core-to-mantle heat flow.