Fast-growth thermodynamic integration: Error and efficiency analysis

Equilibrium free energy differences can be calculated accurately from repea ted fast-growth thermodynamic integration (TI) based on Jarzynski's identit y [Phys. Rev. Lett. 78, 2690 (1997)]. We derive expressions for the free en ergy differences. Error estimates allow us to quantify the relative efficie ncy of performing many fast-growth vs few slow-growth TIs for a given total computational cost. Fast-growth TI is illustrated through the calculation of the potential of mean force between two methane molecules and compared t o umbrella sampling analyzed by using the weighted histogram analysis metho d. Fast-growth TI is well suited for parallel computer architectures, requi ring only the simplest parallelism with repeated runs for different startin g conditions. (C) 2001 American Institute of Physics.