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ao_two_e_erf_ints
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Here, all two-electron integrals (:math:`erf(\mu r_{12})/r_{12}`) are computed.
As they have 4 indices and many are zero, they are stored in a map, as defined
in :file:`utils/map_module.f90`.
The main parameter of this module is :option:`ao_two_e_erf_ints mu_erf` which is the range-separation parameter.
To fetch an |AO| integral, use the
`get_ao_two_e_integral_erf(i,j,k,l,ao_integrals_erf_map)` function.
The conventions are:
* For |AO| integrals : (ij|kl) = (11|22) = = <12|12>