Addition/Correction pubs.acs.org/JPCB
Correction to “Free Energy Reconstruction in Bidirectional Force Spectroscopy Experiments: The Effect of the Device Stiffness” Simone Marsili and Piero Procacci* J. Phys. Chem. B 2010, 114 (7), 2509−16. DOI: 10.1021/jp908663z In eq 7 there is a missing term in the logarithm argument. The free energy profile Gm(r) of the system should be defined with respect to an immaterial reference distance r* as ⎛ Z (r ) ⎞ Gm(r ) = −kBT ln⎜ m ⎟ ⎝ Zm(r*) ⎠
(1)
−βH(x)
where Zm(r) = ∫ e δ[r − r(x)] dx. Equation 6 can be thus worked out as follows: P(r |λ) =
∫ e−β{H(x) + V [r(x) − λ]}δ[r − r(x)] dx
= e βG(λ)
Z(λ )
∫ e−βH(x)e−βV [r(x) − λ)]δ[r − r(x)] dx
Zm(r ) * βG(λ) −βV (r − λ) Zm(r ) e =e Zm(r ) * Zm(r ) * = e βG(λ)e−βV (r − λ)e−βGm(r)Zm(r ) *
Zm(r ) *
(2)
Equation 7 must be therefore corrected as P(r |λ) Zm(r ) (3) * When free energy dif ferences are evaluated with eq 3 (as done in eq 14), the Zm(r*) term cancels out so that the results in the paper are unaffected by the correction. G(λ) = Gm(r ) + V (r − λ) + kBT ln
Published: July 7, 2016 © 2016 American Chemical Society
7037
DOI: 10.1021/acs.jpcb.6b06166 J. Phys. Chem. B 2016, 120, 7037−7037
