另外https://manual.q-chem.com/5.2/Ch12.S2.html
”. Q-Chem employs a Switching/Gaussian or “SWIG” implementation of these PCMs.523, 524, 525, 373, 521 This approach resolves a long-standing—though little-publicized—problem with standard PCMs, namely, that the boundary-element methods used to discretize the solute/continuum interface may lead to discontinuities in the potential energy surface for the solute molecule. These discontinuities inhibit convergence of geometry optimizations“ 可能隐式优化在一些程序包里就是比较困难
https://www.orcasoftware.de/tutorials_orca/prop/CPCM.html
"The usual point charge scheme might lead to instabilities in the energy, e.g. if two points end up too close. In ORCA, we use a smeared Gaussian charge to obtain a smoother potential energy surface [Karplus1999] [Neese2020] instead."