A is the set of attributes (q, σ , ε, λ ), f GP,a,M(i) is the value of attribute a of the ghost particle that maps to target atom i, and f T,a,i is the value of attribute a of target atom i. Appropriate values for Φ a were determined by increasing their value until adequate convergence of the attributes was achieved. The factors {Φ a } are given in Table . Finally, another feature of the integrator used here is that it keeps the sum of the ghost particle partial charges equal to a constant value, which is set to zero for all molecules simulated here, but could be set to an integer value for charged molecules.