I am currently working on simulating a system of deep eutectic solvent (DES) composed of choline chloride and urea in a 1:2 molar ratio. As I am new to using the GROMACS simulation package, I am attempting to reproduce the results from the literature: DOI: 10.1021/acs.jpcb.8b06647.
Following energy minimization, I performed equilibration under the NVT ensemble using the V-rescale thermostat for 1 ns. This was followed by a 5 ns equilibration under the NPT ensemble using the Berendsen barostat.
During the NVT equilibration, the system exhibited stable temperature fluctuations, with an average temperature close to the target value of 298.15 K. However, during the NPT equilibration, I observed significant pressure fluctuations (exceeding ±1000 bar), and the system temperature also began to drift upward, fluctuating around 330 K—despite setting the reference temperature to 298.15 K. Additionally, the log file displayed a warning indicating that the pressure coupling deviation exceeded 1%.
Could someone kindly help me understand the cause of these instabilities and guide me on how to correct the setup?
