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Determination of thermal transport properties from first principles

DOI: 10.1615/ICHMT.2015.IntSympAdvComputHeatTransf.1920
page 1810

Keivan Esfarjani
Mechanical Engineering, Rutgers University, Piscataway, New Jersey, USA; IAMDN, Rutgers University, Piscataway, New Jersey, USA

Sinopsis

We have developed in the past decade a methodology to determine the lattice thermal conductivity of bulk crystalline materials from first-principles. The inputs to this lattice dynamics theory are obtained from density-functional theory (DFT) calculations of forces for given atomic displacements. This theory has been successfully applied to compute the phonon relaxation times, mean free paths (MFPs) and thermal conductivity of several compounds such as Si, Ge, GaAs, PbTe, PbSe, GeSe, ZrCoSb ...

The methodology was further extended to compute the phonon transmissivity across an interface such as in GaAs/AlAs or Si/Ge. Using this approach, we were also successful in predicting the separate contributions of coherent and incoherent phonons to the thermal conductivity of superlattices. Having the information on bulk phonon MFPs, group velocities and interfacial transmissions allows a multiscale formulation of lattice thermal conductivity of polycrystalline materials, which are commonly used as thermoelectrics.

Finally, this approach was extended to describe and unify near-field radiation and conduction across a nanoscale gap between two flat surfaces. It has the advantage of continuously describing thermal conduction from contact (conduction) limit to non-contact (radiation) limit, all within the same formalism.

In this talk we will describe the above methodologies and discuss some of the outstanding results obtained using this approach.

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