In most SMD schemes, constant-velocity SMD (CV-SMD) has been widely applied to various molecular systems and has succeeded in investigating unbinding events. In CV-SMD, an external force that depends on time is applied to a molecule to enhance its dissociation. CV-SMD has been combined with Jarzynski equality or the cumulant expansion of the equality to estimate free energy . Recent studies have shown that the binding free energy calculated by CV-SMD with Jarzynski equality leads to a good correlation with the experimental binding free energy .