get_c6_from_system

get_c6_from_system(ket_tuple, system_pair, unit=None)[source]

Calculate the \(C_6\) coefficient for a given tuple of ket states.

This function calculates the \(C_6\) coefficient in the desired unit. The input is a 2-tuple of single atom ket states.

Parameters:

  • ket_tuple (Union[KetPairReal, KetPairComplex, tuple[KetAtom, KetAtom], Sequence[KetAtom]]) – The input is a tuple repeating the same single atom state in the format (a,a).

  • given (If a tuple with not exactly two identical states is)

  • raised. (a ValueError is)

  • 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 \(C_6\) coefficient. If a unit is specified, the value in this unit is returned.

Raises:

ValueError – If a tuple with more than two single atom states is given.