walter-feng / cc_wick_parser

A parser that helps contract the creation/annihilation operators with phase factor

CC-Wick-Parser

A parser that helps contract the creation/annihilation operators with phase factor.

This repository follows the style of numpy's einsum function that automatically parses the symbols in a string. It implements the Wick's theorem, taking good care of the phase factor for each term, with consideration to the occupied / virtual orbitals during the contraction. The symbols follow the convention of

"a", "b", .... -> virtual
"i", "j", .... -> occupied
"p", "q", .... -> general

which can also be customized.

Should be good to go directly running the unit test, after exporting- the directory to this repository- to $PYTHONPATH.