In the second example we used Stochastic-GAS to perform a very large uncontracted stochastic-MRCISD calculation (using the RAS strategy) on an Fe(II)-porphyrin model system, where a total of 96 electrons and 159 orbitals have been correlated over a (32, 34) RAS2 space. While the RAS2 space accounts for relatively strong forms of electron correlation, as we have discussed already in earlier works, single and double excitations out of the occupied space (RAS1) and into the virtual orbitals (RAS3) account for dynamic correlation. By considering both static and dynamic electron correlation, we could greatly improve the theoretical estimate for the spin gap between the 5 A 1g and 3 E g state to be around (6.8 ± 0.1) kcal mol -1 , substantially larger than our previous estimate exclusively based on the Stochastic-CASSCF (32, 34) energetics. This application shows how Stochastic-GAS can be utilized to account for dynamic correlation in a systematically improvable way, as opposed to other methodologies such as DFT 100,101 or MC-PDFT 102 that rely on the accuracy of (translated) functionals to describe exchange and correlation effects.