Dear CP2k'lers, related to a previous post (<a href="https://groups.google.com/d/topic/cp2k/iMsqLpZnRyQ/discussion">https://groups.google.com/d/topic/cp2k/iMsqLpZnRyQ/discussion</a>) I just wanted to highlight the main problems again, because they might have been hidden in the mess. The QMMM electrostatic coupling is different for different Poisson solvers if analogous inputs with Wavelet and Multipole solver are used. In the example from the previous post (using Multipole solver) the QM images are recoupled. If one just changes the Poisson solver to the Wavelet solver, no recoupling of the QM images is performed. This behaviour then further depends on the inclusion/exclusion of the non-optional section %FORCE_EVAL%QMMM%PERIODIC. The input can be changed in a way that one reproduces the total energies with both Poisson solvers (up to ~0.01 eV). This behaviour is counterintuitive, imo, and I would appreciate comments of the developers, if it is intended, if I am doing something wrong etc pp Cheers, Frank