Dear all, I'm trying to reproduce the hydration free energy of the methanol using the CHARMM force field. However I am getting a value considerably lower than the experimental: 17 kJ mol-1 (the experimental value is 21 kJ mol-1).
Am I forgetting some technicality related to the force field? I using a detailed thermodynamic integration procedure, where I decouple Couloumb and van der Waals interactions separately, at lambda intervals of 0.04. I'm using sd integrator and softcore to decouple van der Waals interactions. Other details: NPT, box with 1000 TIP3P water molecules and one methanol molecule, 400ps per window. In a general review I noticed that is not easy to obtain good accuracies in this property. For example, the original paper (J Comput Chem 29: 2543, 2008), is reported a overestimated value of 23.9 kJ mol-1. In J Phys Chem B 110: 17616, 2006, Hess got a underestimated result by 2 kJ mol-1. Shits reported a value of 18.87 kJ mol-1 in J Chem Phys 122: 134508, 2005. These inexact values is inherent to the models or there was any way to improve the accuracy through the protocol used? Bests eef _______________________________________ Eudes Eterno Fileti Instituto de Ciência e Tecnologia da UNIFESP Rua Talim, 330, São José dos Campos - SP Tel.: (12) 3309-9573 Página: sites.google.com/site/fileti/ -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Only plain text messages are allowed! * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
