Path-integral imaginary-time TDDFT simulation of the hydrogen-bonded systems*

We have recently developed a new imaginary-time time-dependent density-functional theory (itTDDFT)-based approach for computing the ground-state electron-ionic structure of atomistic systems[1]. In this method the ionic degrees of freedom are treated in the path-integral formalism, whereas electronic degrees of freedom are treated with itTDDFT. Our method, given an exact functional of the electronic density, is in principle exact in the zero-temperature limit. With approximate functionals it offers a practical path to direct ab initio simulation of molecular and condensed matter systems going beyond the Born-Oppenheimer approximation. In this work we apply our method to study properties of hydrogen-bonded and tautomeric molecules: hydrogen sulfide, formic acid and terephthalic acid dimers. We compare the results of our simulations to known experimental and theoretical results.

[1] Kolesov G, Kaxiras E, Manousakis E. Density functional theory beyond the Born-Oppenheimer approximation: accurate treatment of the ionic zero-point motion. arXiv:1804.10852. Accepted at Phys. Rev. B (2018)