Correction to Constant pH Molecular Dynamics in Explicit Solvent with λ-Dynamics

which replaces eq 33. We note that in our implementation of the constant pH protocol, the expressions for the forces due to V(λ1,λ2) and V(λ1,λ2) were implemented correctly; thus the trajetories are unaffected. The above corrected expressions are required only to compute the total energy of the system (i.e., the real and λ particles together) during the simulation. As a test, we have computed a 1 ns constant pH trajectory of imidazole in water (≈ 15 700 atoms) in the microcanonical ensemble. In the simulation, nonbonded interactions were evaluated with a 1.3 nm cutoff. Between 1 nm and the 1.3 nm cutoff, forces were smoothly shifted to zero using a shift function. We observed that the total energy of the complete system is constant with an average of −177 723 kJ mol−1 and a standard deviation of 0.3 kJ mol−1. As the time step was decreased from 0.5 fs to 0.25 fs and 0.1 fs, the standard deviation decreased from 0.3 kJ mol−1 to 0.07 kJ mol−1 and 0.01 kJ mol−1, respectively, thus establishing proper conservation of total energy. ■ AUTHOR INFORMATION Corresponding Author *E-mail: hgrubmu@gwdg.de (H.G.), ggroenh@gwdg.de (G.G.). Present Address †Institute of Computer Science, Georg August University, Göttingen, Germany.