Dear CP2K Developers, I am looking into using the Gibbs Ensemble Monte Carlo (GEMC) methos in CP2K to compute the liquid-vapor phase diagram using a fully DFT-based method.However, I have problems stabilizing liquid and vapor phases when doing simulations fully ab intio, as described below. By taking input files for water from <a href="https://www.cp2k.org/howto:gemc">https://www.cp2k.org/howto:gemc</a> and minimally changing them, I was able to run the GEMC model and get sensible results for water. This input utilizes the BLYP functional and an empirical model for pre-sampling, employing the FIST methods as specified in the bias_template.inp file. The input files and the output mc_molecules file are attached. The latter file shows how many molecules are present during the GEMC run in the liquid phase (between 64 and 62 water molecules) and the gas phase (between 0 and 2 water molecules). The problem starts where I substitute the empirical potential for water with the actual BLYP method in the bias_template.inp file (I renamed that file to be bias_template-DFT.inp). Please note that I keep all other settings the same as before, but only substituting the empirical water model with the DFT model. Now, the results of simulations have no sense. The water molecules from the liquid box move to another gas phase box until two phases have roughly the same number of water molecules. The mc_molecules-DFT shows this problem. Using fully DFT calculations is supposed to give very similar or slightly improved results, but instead it produces very different and unexpected results. It looks like that replacing the FIST model with the DFT model causes some changes in the program that treats swapping molecules between the two boxes differently (almost like allowing them to swap only one way). At this stage, it is crucial to consult CP2K developers to identify the factors that contribute to a significant change in the software's behavior when transitioning from the utilization of the empirical potential in bias_template.inp to using DFT. Thank you, Slava Vyacheslav Bryantsev Chemical Separations Group Oak Ridge National Laboratory -- You received this message because you are subscribed to the Google Groups "cp2k" group. To unsubscribe from this group and stop receiving emails from it, send an email to <a href="mailto:cp2k+unsubscribe@googlegroups.com">cp2k+unsubscribe@googlegroups.com</a>. To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/d1e0bbdb-99a1-4578-a01a-8f914aa5bd62n%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/d1e0bbdb-99a1-4578-a01a-8f914aa5bd62n%40googlegroups.com</a>.