title: A first-principles study on the phonon transport in layered BiCuOSe.
abstract: First-principles calculations are employed to investigate the phonon transport of BiCuOSe. Our calculations reproduce the lattice thermal conductivity of BiCuOSe. The calculated grüneisen parameter is 2.4 ~ 2.6 at room temperature, a fairly large value indicating a strong anharmonicity in BiCuOSe, which leads to its ultralow lattice thermal conductivity. The contribution to total thermal conductivity from high-frequency optical phonons, which are mostly contributed by the vibrations of O atoms, is larger than 1/3, remarkably different from the usual picture with very little contribution from high-frequency optical phonons. Our calculations show that both the high group velocities and low scattering processes involved make the high-frequency optical modes contribute considerably to the total lattice thermal conductivity. In addition, we show that the sound velocity and bulk modulus along a and c axes exhibit strong anisotropy, which results in the anisotropic thermal conductivity in BiCuOSe.
authors.affiliation: Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
authors.forename: Hezhu
authors.initials: H
authors.lastname: Shao
authors.affiliation: Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Tan
authors.affiliation: Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Liu
authors.affiliation: Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
authors.forename: Haochuan
authors.initials: H
authors.lastname: Jiang