  Molecular ferroelectrics have captured immense attention due to their
superiority over inorganic oxide ferroelectrics, such as environmentally
friendly, low-cost, flexible, foldable. However, the mechanisms of
ferroelectric switching and phase transition for the molecular ferroelectrics
are still missing, leaving the development of novel molecular ferroelectrics
less efficient. In this work, we have provided a methodology combining
molecular dynamics (MD) simulation on a polarized force field named polarized
crystal charge (PCC) and enhanced sampling technique, replica-exchange
molecular dynamics (REMD) to simulate such mechanisms. With this procedure, we
have investigated a promising molecular ferroelectric material,
(R)/(S)-3-quinuclidinol crystal. We have simulated the ferroelectric hysteresis
loops of both enantiomers and obtained spontaneous polarization of 7/8 \mu C
cm-2 and a corresponding coercive electric field of 15 kV cm-1. We also find
the Curie temperature as 380/385 K for ferro-/para-electric phase transition of
both enantiomers. All of the simulated results are highly compatible with
experimental values. Besides of that, we predict a novel Curie temperature of
about 600 K. This finding is further validated by principal component analysis
(PCA). Our work would significantly promote the future exploration of
multifunctional molecular ferroelectrics for the next generation of intelligent
devices.
