I wish to perform an restricted-openshell MP2 (roMP2) optimization. Gaussian09 currently only provides energies at roMP2 level of theory. It should be possible to perform an optimization by displacement of the structure followed by single-point-energy evaluations at the displaced geometries to obtain a gradient. In other quantum-chemical software packages this (slower) numerical optimization technique is readily available. I cannot seem to get it to work in the case of roMP2 in Gaussian09. I have already tried the usual options, such as "#p opt roMP2/cc-pVDZ scf=tight" and so on. All of my approaches failed. Any help or pointers towards other software that is capable of roMP2 optimizations would be appreciated.