Liquid stability in a model for ortho-terphenyl.

Area of Science:

• Thermodynamics and Statistical Mechanics
• Condensed Matter Physics
• Computational Chemistry

Background:

• Understanding the liquid state's stability is crucial for materials science.
• Previous studies on ortho-terphenyl models were limited in density and temperature ranges.

Purpose of the Study:

• To extensively map the phase diagram of a simple ortho-terphenyl model.
• To determine the limits of liquid state stability.
• To investigate the relationship between potential energy landscape and thermodynamic properties.

Main Methods:

• Extensive simulation of the ortho-terphenyl model across varied densities and temperatures.
• Estimation of homogeneous liquid-gas nucleation line and spinodal locus.
• Analysis of potential energy landscape using statistical properties of minima.
• Calculation of volume dependence for Gaussian distribution parameters.

Main Results:

• The study extends phase diagram data to lower/higher densities and higher temperatures.
• Potential energy landscape minima exhibit Gaussian distribution properties over a wide volume range.
• Volume dependence of Gaussian distribution parameters (amplitude, average energy, variance) is reported.
• The Kauzmann line (vanishing configurational entropy) is evaluated and compared with the spinodal locus.

Conclusions:

• The statistical properties of the potential energy landscape are consistent with a Gaussian distribution of minima.
• The study provides a comprehensive understanding of ortho-terphenyl's liquid state stability.
• The relative positions of the spinodal and Kauzmann lines offer insights into the glass transition mechanism.