Dissociation of Sarin on a Cement Analogue Surface: Effects of Humidity and Confined Geometry

CJ O'Brien and JA Greathouse and CM Tenney, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 28100-28109 (2016).

DOI: 10.1021/acs.jpcc.6b10046

First-principles molecular dynamics simulations were used to investigate the dissociation of sarin (GB) on the calcium silicate hydrate (CSH) mineral tobermorite (TBM), a surrogate for cement. CSH minerals (including TBM) and amorphous materials of similar composition are the major components of Portland cement, the binding agent of concrete. Metadynamics simulations were used to investigate the effect of the TBM surface and confinement in a microscale pore on the mechanism and free energy of dissociation of GB. Our results indicate that both the adsorption site and the humidity of the local environment significantly affect the sarin dissociation energy. In particular, sarin dissociation in a low-water environment occurs via a dealkylation mechanism, which is consistent with previous experimental studies.

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