One-dimensionally confined ammonia molecules: A theoretical study

TL;DR

This study investigates the behavior of ammonia molecules confined in a one-dimensional chain within a carbon nanotube, revealing orientational quasiorder at low temperatures through simulations and lattice models.

Contribution

It combines molecular dynamics and lattice-model calculations to analyze ammonia orientation in nanotubes, providing new insights into molecular ordering under confinement.

Findings

Ammonia molecules exhibit orientational quasiorder below 100 K.

The molecules tend to align parallel to the nanotube axis.

The study demonstrates the effectiveness of combined simulation and lattice models.

Abstract

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.