Nuclear quantum effects on autoionization of water isotopologs studied by <i>ab initio</i> path integral molecular dynamics

In this study, we investigate the nuclear quantum effects (NQEs) on acidity constant (pKA) of liquid water isotopologs under ambient condition by path integral molecular dynamics (PIMD) simulations. We compared simulations using a fully explicit solvent model with classical polarizable force field, density functional tight binding, and ab initio theory, which correspond to empirical, semiempirical, PIMD simulations, respectively. The centroid variable respect proton coordination number molecule was restrained compute gradient free energy, measures reversible work abstraction for mechanical system. energy curve obtained thermodynamic integration used pKA value based probabilistic determination. This technique not only reproduces D2O experimentally measured (14.86) but also allows theoretical prediction values T2O aqueous HDO HTO, are unknown due their scarcity. It is shown that NQEs can result in downshift 4.5 ± 0.9 units case water, indicates plays an indispensable role absolute determination pKA. results study help inform further extensions into calculation constants isotope substituted species high accuracy.