FMGCs will automatically compute the OEI Green Dot but not your Vapp as its value may be influenced by many factors unknown to it.
For OEI (and ENG FIRE p/b pushed+ice acc), refer to QRH 2.33 and 2.31 for your Vapp.
OEI condition without damage, there is no need to compute another Vapp than the one displayed on MCDU for your config.