get_c3_from_system

get_c3_from_system(ket_tuple_list, system_pair, unit=None)[source]

Calculate the \(C_3\) coefficient for a list of two 2-tuples of single atom ket states.

This function calculates the \(C_3\) coefficient in the desired unit. The input is a list of two 2-tuples of single atom ket states. We use the convention \(\Delta E = \frac{C_3}{r^3}\).

Parameters:

ket_tuple_list (Collection[Union[KetPairReal, KetPairComplex, tuple[KetAtom, KetAtom], Sequence[KetAtom]]]) – The input as a list of tuples of two states [(a,b),(c,d)], the \(C_3\) coefficient is calculated for (a,b)->(c,d). If there are not exactly two tuples in the list, a ValueError is raised.
system_pair (Union[SystemPairReal, SystemPairComplex]) – The pair system that is used for the calculation.
unit (Optional[str]) – The unit to which to convert the result. Default None will return a pint quantity.

Return type:

Union[float, PlainQuantity[float]]

Returns:

The \(C_3\) coefficient with its unit.

Raises:

ValueError – If a list of not exactly two tuples of single atom states is given.