import numpy as np
from pyscf import gto, scf, ao2mo, dft

def compute_coulomb_integrals(mol):
    eri = mol.intor('int2e')
    return eri

def compute_exchange_integrals(mol):
    eri = mol.intor('int2e')
    return eri

def compute_JK_coupling(mol1, mol2):
    eri1 = compute_coulomb_integrals(mol1)
    eri2 = compute_exchange_integrals(mol2)
    return eri1, eri2

def compute_coupling_term(mol1, mol2):
    eri1, eri2 = compute_JK_coupling(mol1, mol2)
    # Compute DFT XC contributions
    dft_obj = dft.RKS(mol1)
    dft_obj.xc = 'lda,vwn'
    dft_obj.grids.atom_grid = (99, 590)
    dft_obj.grids.prune = None
    dft_obj.kernel()
    xc_energy = dft_obj.exc
    coupling_term = eri1 + eri2 + xc_energy
    return coupling_term

def evaluate_overall_coupling_term(mol1, mol2):
    coupling_term = compute_coupling_term(mol1, mol2)
    overall_coupling = np.sum(coupling_term)
    return overall_coupling

# Perform CIS calculations for excited states of two molecules
mol1 = gto.M(atom='H 0 0 0; H 0 0 1', basis='sto-3g')
mol2 = gto.M(atom='H 0 0 0; H 0 0 1', basis='sto-3g')
mf1 = scf.RHF(mol1).run()
mf2 = scf.RHF(mol2).run()

# Calculate intermolecular 2e integrals
eri1 = ao2mo.outcore.general(mf1._eri, (mf1.mo_coeff,) * 4).reshape(mf1.mo_coeff.shape * 2)
eri2 = ao2mo.outcore.general(mf2._eri, (mf2.mo_coeff,) * 4).reshape(mf2.mo_coeff.shape * 2)

# Transform integrals to MO basis
eri1_mo = np.einsum('pqrs, pt, qv, rs -> tv', eri1, mf1.mo_coeff, mf1.mo_coeff, mf1.mo_coeff)
eri2_mo = np.einsum('pqrs, pt, qv, rs -> tv', eri2, mf2.mo_coeff, mf2.mo_coeff, mf2.mo_coeff)

# Compute J-type and K-type coupling
J_type_coupling = np.einsum('ij, ij ->', eri1_mo, eri2_mo)
K_type_coupling = np.einsum('ij, ij ->', eri1_mo, eri2_mo)

# Evaluate overall coupling term
overall_coupling_term = evaluate_overall_coupling_term(mol1, mol2)