Using Conventional Unit Cell in Anphon Calculation

[zohansyahfatomi]

Dear Admin,

My name is Zohan.
I am a Graduate Student at Kanazawa University.
I can not find the primitive cell in my structure.
My structure is SnSe (8 atoms: 4 Se and 4 Sn).

Sn4 Se4
1.0
4.1262509500000002 0.0000000000000000 0.0000000000000003
0.0000000000000008 4.7009074499999999 0.0000000000000003
0.0000000000000000 0.0000000000000000 11.6644585000000003
Sn Se
4 4
direct
0.7500000000000000 0.3765543000000000 0.6187868500000000 Sn2+
0.2500000000000000 0.8765543000000000 0.8812131500000000 Sn2+
0.2500000000000000 0.6234457000000000 0.3812131500000000 Sn2+
0.7500000000000000 0.1234457000000000 0.1187868500000000 Sn2+
0.2500000000000000 0.5091818000000000 0.1485530300000000 Se2-
0.2500000000000000 0.9908182000000000 0.6485530300000000 Se2-
0.7500000000000000 0.0091817999999999 0.3514469700000000 Se2-
0.7500000000000000 0.4908182000000000 0.8514469700000000 Se2-

Is it possible to use a conventional unit cell for anphon calculation?
Thank you very much.

Sincerely yours,
Zohan

[ttadano]

In version 1.x.y of ALAMODE, using non-primitive cell is not supported because the anphon code internally detects a primitive cell and use it for further calculations.

In version 2.x (currently developed under 2.0dev branch), it is possible to use a non-primitive cell . If you are interested, please try 2.0dev.

[xinyu1905]

I am sorry, my question differs from the original one. I would like to know how to obtain the force constants for a non-primitive cell. When ALAMODE calculates the force constants, it converts the non-primitive cell into a primitive cell. For instance, if the conventional cell contains 10 atoms, the primitive cell contains 5 atoms, and the supercell contains 60 atoms, ALAMODE provides force constants in a 5 x 60 format. However, I need the force constants in a 10 x 60 format. How should I proceed?

[ttadano]

I understand your question.

Unfortunately, ALAMODE does not have the option to print the force constants in the format you requested. However, it is easy to convert the 5x60 format into 10x60 since you just need to translate all atoms by the lattice translation vector.

[xinyu1905]

Thank you very much, I have successfully completed the conversion. By the way, since the higher-order force constants are also based on the primitive cell, if I want to use the 2nd, 3rd, and 4th-order force constants in ShengBTE calculations, the 2nd-order force constants need to be adapted to the supercell. For example, if I need to convert the 5 x 60 force constants to 40 x 40 force constants (with the primitive cell expanded to 2 x 2 x 2), how should I proceed?

[ttadano]

I'm not sure if I understand your question, but basic stragegy remains the same; you just need to translate all atom triples (ijk) or quartets (ijkl) by the lattice translation vectors that span the supercell.

[xinyu1905]

Thank you for your suggestion, I will try it.

[zohansyahfatomi]

Dear Prof. Tadano,

Thank you for the reply.
I plan to download the version of 2.x, however in https://sourceforge.net/projects/alamode/, I think it is version 1.x. How to get the version of 2.x?
Thank you very much.

Sincerely yours,
Zohan

[gangliu-github]

U can find 2.x in https://github.com/ttadano/alamode/branches