Function vac_av(ExprPtr, const OpConnections<mbpt::OpType>&, bool)¶

Function Documentation¶

ExprPtr vac_av(ExprPtr expr, const OpConnections<mbpt::OpType> &op_connections = default_op_connections(), bool skip_clone = false)¶

computes the vacuum expectation value (VEV)

Parameters:

expr – [in] input expression
op_connections – [in] list of pairs of operators to be connected; connections are left-to-right, i.e., pair {opL,opR} declares that opL and opR are to be connected when opR precedes opL, i.e. opL is to the left of opR; e.g., {{OpType::h, OpType::t}} will ensure that each OpType::h will be connected to at least one OpType::t on its right (preceding it). The default list of connections is given by default_op_connections() .
skip_clone – [in] if true, will not clone the input expression

Returns:

the VEV