quemb.shared.helper.get_flexible_n_eri

quemb.shared.helper.get_flexible_n_eri(p_max, q_max, r_max, s_max)

Return the number of unique ERIs but allowing different number of orbitals.

This is for example the situation for a tuple \(\mu, \nu, \kappa, i\), where \(\mu, \nu, \kappa\) are AOs and \(i\) is a fragment orbital. This function returns the number of unique ERIs \(g_{\mu, \nu, \kappa, i}\).

Parameters:

• p_max (TypeVar(_T_Integral, bound= int | integer))

• q_max (TypeVar(_T_Integral, bound= int | integer))

• r_max (TypeVar(_T_Integral, bound= int | integer))

• s_max (TypeVar(_T_Integral, bound= int | integer))

Return type:

TypeVar(_T_Integral, bound= int | integer)