Volodymyr Krasnov | Searcharxiv

arXiv2023

One-dimensionally confined ammonia molecules: A theoretical study

We examine a single-file chain of ammonia molecules in a carbon nanotube. To this end, we use i) molecular dynamics simulations (combined with the charges for ammonia nitrogen and hydrogen obtained from quantum chemistry) and ii) lattice-model calculations [M.~Druchok {\it et al.}, J. Chem. Phys. {\bf 158}, 104304 (2023)]. Our findings demonstrate the occurrence of the orientational quasiorder of the ammonia dipoles, which become parallel to the tube axis, at intermediate temperatures below $100$~K.

cond-mat.stat-mech↗

arXiv2023

Towards a quasiphase transition in the single-file chain of water molecules: Simple lattice model

Recently, X.Ma et al. [Phys. Rev. Lett. 118, 027402 (2017)] have suggested that water molecules encapsulated in (6,5) single-wall carbon nanotube experience a temperature-induced quasiphase transition around 150 K interpreted as changes in the water dipoles orientation. We discuss further this temperature-driven quasiphase transition performing quantum chemical calculations and molecular dynamics simulations and, most importantly, suggesting a simple lattice model to reproduce the properties of the one-dimensionally confined finite arrays of water molecules. The lattice model takes into account not only the short-range and long-range interactions but also the rotations in a narrow tube and the both ingredients provide an explanation for a temperature-driven orientational ordering of the water molecules, which persists within a relatively wide temperature range.

cond-mat.stat-mech↗