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Hengtai Zheng

Publications and source records attributed to Hengtai Zheng.

2 recordsLinked to original sources
arXiv2026

Heat Transport Mechanisms in MOF-5

We find that MOF-5 supports both long-lived phonons and linker vibrations whose split spectra signal a breakdown of the phonon quasiparticle approximation. Combining mode-projected molecular dynamics spectra with spectral Wigner heat transport, we resolve two contrasting transport channels: low-frequency particle-like phonon propagation decreases strongly from 200 to 500 K, whereas wave-like phonon coherence remains nearly constant and supplies about half the intrinsic conductivity at 500 K. A phenomenological extrinsic scattering model provides a plausible explanation for the discrepancy between calculated and measured conductivities in terms of both its magnitude and temperature dependence. We also identify signatures of phonon quasiparticle breakdown in the linker vibrations of ZIF-8 and HKUST-1, indicating that this feature extends to other metal-organic frameworks.

cond-mat.mtrl-sci↗
arXiv2026

Nuclear quantum effects in the thermal conductivity of solid hydrogen

We use a combination of path integral and lattice dynamics methods to calculate the thermal conductivity of solid parahydrogen. Path integral molecular dynamics is first used to calculate a centroid potential of mean force at each temperature, on which a harmonic phonon basis is constructed using the finite displacement method. We then calculate anharmonic force constants on the centroid potential and solve the linearised phonon Boltzmann transport equation for the thermal conductivity. The resulting renormalised phonon dispersion curves, heat capacity, and thermal conductivity are all in remarkably good agreement with experimental measurements. We find that the heat transport is dominated by collective relaxon modes at low temperatures and cannot be captured by making the phonon relaxation time approximation. Indeed, quantitative agreement with the experimental thermal conductivity is only achieved when the nuclear quantum effects in the centroid potential of mean force, phonon boundary scattering, and hydrodynamic transport are all explicitly considered. This is also likely to be the case for other quantum crystals.

cond-mat.mtrl-sci↗