Array Parser

For many different tasks performed in the PM suite, a vector or matrix must be provided at the command line or in a yaml file. PM has an array parser which allows substantial flexibility to facilitate this (see parse_array if interested in the details).

Consider entering the lattice vectors tag. All of the below are valid syntax. The parser excepts delimiters: line break, semi-colon, comma, space, where line break takes highest position. If only one delimiter is present, the result will be a vector, while two delimiters yields a matrix, etc.

lattice_vectors: 
  [[0.000000,2.764309,2.764309],
   [2.764309,0.000000,2.764309],
   [2.764309,2.764309,0.000000]]

lattice_vectors: |
   0   1/2 1/2
   1/2 0   1/2
   1/2 1/2 0

lattice_vectors: 0 1/2 1/2 ; 1/2 0 1/2 ; 1/2 1/2 0
lattice_vectors: 0 1/2 1/2 , 1/2 0 1/2 , 1/2 1/2 0
lattice_vectors: 0,1/2,1/2 ; 1/2,0,1/2 ; 1/2,1/2,0
lattice_vectors: 0,1/2,1/2;1/2,0,1/2;1/2,1/2,0

lattice_vectors: |
    a=1.8 c=10
    a*r3/2  a/2 0
    a*r3/2 -a/2 0
    0       0   c

In the last example, a substition is being performed, where the first line contains variable definitions.

One test this on the command line as follows:

$ pm-lattice --lattice-vectors '1 0 0 ; 0 1 0 ; 0 0 1' --print-attribute lattice_vectors
lattice_vectors:
  [[ 1.00000000,  0.00000000,  0.00000000],
   [ 0.00000000,  1.00000000,  0.00000000],
   [ 0.00000000,  0.00000000,  1.00000000]]