Unexpected Suppression of Double-Proton Tunneling Induced by Quantum Barriers from Zero-Point Energy.

ABSTRACT: To assess tunneling, we studied the guanine-cytosine (GC) base pair tautomerization in the gas phase. We applied multidimensional semiclassical reaction path methodology with microcanonically optimized multidimensional tunneling (μOMT) using POLYRATE. The minimum energy path (MEP) has a single saddle point for the double proton transfer. Addition of vibrational zero-point energy (ZPE) to the MEP gives the vibrationally adiabatic ground state curve, V_a^G, which is the barrier through which tunneling occurs. Unexpectedly, V_a^G has not one but two well-separated barriers in the transition state region. The first is near the saddle point. The second barrier is entirely due to a large amount of ZPE associated with local reaction path curva

SUBMITTER: Greer EM 

PROVIDER: S-EPMC12322913 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature