Phono3py is a program written in Python that enables the calculation of lattice thermal conductivity of materials, along with other properties obtainable from the 3rd order force constants. Force constants are obtained using the finite displacement method. The finite displacement method uses the forces on atoms resulting from one or more atoms displaced from their equilibrium position to obtain the force constants. For more details on the theory, see the author’s paper. This guide is written for Phono3py version 1.13.3 and aimed to work in the computing clusters at Aalto CMAT. For further details and possible changes in functionalities in future versions, please see the Phono3py home page.
If you are not familiar with Phonopy beforehand, it is recommended to see the Phonopy tutorial first, as the usage is very similar to Phono3py and knowing your way around the program will help in focusing on the new aspects and features. The workflow of Phono3py is practically identical to Phonopy, and it is laid out on the wiki page of Phonopy with the exception that Phono3py also calculates the 3rd order force constants.
These instructions will help you use Phono3py with the Phono3py-CRYSTAL interface. For other quantum chemical software you will find the list at the Phono3py home page. We will be using outputs from CRYSTAL calculations, and all output files that are needed to follow the examples are also provided for download.
We will use Cu2O in all the worked examples.