Benchmarking of Molecular Dynamics Force Fields for Solid–Liquid and Solid–Solid Phase Transitions in Alkanes

Accurate prediction of alkane phase transitions involving solids is needed to prevent catastrophic pipeline blockages, improve lubrication formulations, smart insulation, and energy storage, as well bring fundamental understanding processes such artificial morphogenesis. However, simulation these challenging therefore often omitted in force field development. Here, we perform a series benchmarks on seven representative molecular dynamics models (TraPPE, PYS, CHARMM36, L-OPLS, COMPASS, Williams, the newly optimized Williams 7B), comparing with experimental data for liquid properties, liquid-solid, solid-solid two prototypical alkanes, n-pentadecane (C15) n-hexadecane (C16). We find that existing overestimate melting points by up 34 K, PYS 7B yielding most accurate results deviating only 2 3 K from experiment. specially design order parameters identify crystal-rotator alkanes. United-atom could produce rotator complete rotational disorder, whereas all-atom using 12-6 Lennard-Jones potential show no even when superheated above point. In contrast, (Buckingham potential) COMPASS (9-6 Lennard-Jones) reproduce crystal-to-rotator transition, model having transition temperature C15.