Abstract
Vapor liquid equilibria (VLE) of organic compounds is governed by weak non-covalent interactions. This presents a significant challenge in predicting VLE using a first principles approach where density functional theory is used to model system potential. However, a dispersion corrected approach has significantly improved the performance of traditional density functionals. Here, we predict the VLE for a nonpolar carbon tetrafluoride (R14) and polar 1,1,1,2-tetrafluoroethane (R134a) via first principles Gibbs ensemble Monte Carlo simulations using PBE-D3 density functional. We find that the saturated liquid density for R14 is slightly under predicted for subcritical temperatures, while for R134a it is under predicted at lower reduced temperatures and over predicted at higher reduced temperatures. In the liquid phase, angle-resolved pair correlation functions indicate slight preference for R143a to align in parallel and antiparallel orientation in the first solvation shell. The vibrational spectra reveal peak broadening in the condensed phase due to solvothermal effects. Overall, we find the PBE-D3 functional performance is better for the nonpolar molecule as compared to the polar one.
| Original language | English |
|---|---|
| Pages (from-to) | 11969-11976 |
| Number of pages | 8 |
| Journal | ChemistrySelect |
| Volume | 2 |
| Issue number | 36 |
| DOIs | |
| State | Published - Dec 21 2017 |
| Externally published | Yes |
Funding
This work is funded by the National Science Foundation (NSF) under grant number CHE - 1265872. We used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number OCI-1053575. XSEDE provided the computing support from the Texas Advanced Computing Center (TACC) at The University of Texas at Austin and University of Tennessee and Oak Ridge National Laboratory’s Joint Institute for Computational Sciences. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract number No. DE-AC02-05CH11231. This research also used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357. At the end, we also acknowledge computational resources at High Performance Computing Collab-oratory at Mississippi State University.
Keywords
- Ab initio calculations
- FPMC
- Fluorinated alkanes
- VLE
- Vibrational spectroscopy