The basis.in input file

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Purpose

This file is used to define the unit cell for phonon calculations.

File format

  • The format of this file must be as follows:
N_basis
id(0) mass(0)
id(1) mass(1)
...
id(N_basis-1) mass(N_basis-1)
map(1)
map(2)
...
map(N)
  • Here,
    • N_basis is the number of atoms in the unit cell you choose. For example, it can be 2 for diamond silicon if you use the primitive cell as the unit cell.
    • The next N_basis lines contain the atom indices (using the order as in the xyz.in file; starting from 0) and masses for the basis atoms. For the example of diamond silicon, id(0)=0 and mass(0)=28 are the index and mass for the first basis atom, and id(0)=4 and mass(0)=28 are the index and mass for the second basis atom.
    • The remaining lines map the atoms in the xyz.in file to the basis atoms. If the n-th atom in the xyz.in file is equivalent to (under translation) the m-th basis atom in the unit cell, we have map(n)=m. In our example, map(n) is either 0 (equivalent to the first basis atom) or 1 (equivalent to the second basis atom).

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