Role of molecular bend angle and biaxiality in the stabilization of the twist-bend nematic phase

Abstract

What are the prerequisites for acquiring a stable twist-bend nematic phase (N_TB)? Addressing this question has led to the synthesis of a vast number of new compounds, concluding each time that the molecule's shape is one of the predominant factors. Inspired by the expanding knowledge of different achiral bent-shaped molecules forming a twist-bend nematic phase, we reinvestigate the interplay between a molecule's bend angle and a molecule's arms molecular biaxiality. Employing our previously developed generalized mean-field model, we explore more obtuse bend angles. We observe direct phase transition sequences between locally biaxial and uniaxial variants of N_TB, along with biaxial and uniaxial nematic phases. Additionally, we present a comprehensive overview of how phase diagrams evolve according to alterations in the value of the bend angle and the magnitude of biaxiality.