1. 1 Thermal conductivity of carbon dioxide from non-equilibrium molecular dynamics Thuat T. Trinh Thuat.T. Trinh, 1 T. J. H. Vlugt, 2 S. Kjelstrup 1 1 Department of Chemistry, NTNU, Norway 2 Delft University of Technology, The Netherlands Kvantekjemi og modellering

2. 2 CO 2 capture @NTNU NTNU Chemical Engineering Department membrane sheets (source http://www.forskningsradet.no) -Carbon membrane -Solid membrane Thermal conductivity of CO 2 at various conditions !

3. 3 Thermal conductivity MaterialData (W m -1 K -1 ), T=25 0 C Silver429 Iron80 Water liquid0.58 Air0.024 CO 2 gas0.015 Molecular simulation by classical Force Field http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

4. 4 Classical force field CO 2 Non-bonded potential: Bonded potential: bond stretching, angle bending

5. 5 Rigid model Vibrational modes of CO 2 (image from http://www.astro.uwo.ca/~jcami/molspec_intro.shtml)

6. 6 Harmonic vs Morse potential DFT: B3LYP/6-311+G(d,p) Morse potential

7. 7 Common force fields (3 site) of CO 2 MSM C. Murthy, K. Singer, and I. McDonald, Mol. Phys. 44, 135 (1981) (Cited 207) EPM2 J. G. Harris, and K. H. Yung, J. Phys. Chem. 99, 12021 (1995). (Cited 626) TraPPE J. J. Potoff, and J. I. Siepmann, AIChE J. 47, 1676 (2001). (Cited 434) EPM2_Flex1: Angle bending, Harmonic bond stretching ( C. Nieto-Draghi, et al., J. Chem. Phys. 126, 064509 (2007)) EPM2_Flex2: Angle bending, Morse bond stretching (this work) Thermal conductivity ? Temperature:300K-1000K, Pressure: 1-200 MPa

8. 8 Non Equilibrium Molecular Dynamics (NEMD) Thermal conductivity from: Boundary driven (NEMD) Ikeshoji and Hafskjold, Molecular Physics, 81, 251-261 (1994). Muller-Plathe method (reverse NEMD) Muller-Plathe, J Chem Phys, 106, 6082 (1997). Green-Kubo formalism (EMD)

9. 9 Simulation box Box size 200x30x30 (Å 3 ), 200-3000 CO 2 Total 300 simulations (T=300K-1000K, 5 FFs) EMD: structure, EOS NEMD: thermal conductivity

10. 10 Distribution of bond and angle of CO 2 ab-initio MD Moumita Saharay et al. ; J. Phys. Chem. B 2007, 111, 387-392. DOI: 10.1021/jp065679t Rigid model

11. 11 Isotherm EOS vs NIST data

12. 12 Temperature and density profile (NEMD) Local equilibrium in NEMD

13. 13 Thermal conductivity at low temperature T=300KT=400K Rigid force field is superior !

14. 14 Flexible force field is superior ! Thermal conductivity at high temperature T=700KT=1000K

15. 15 What model of CO 2 ? Error of rigid models increases with temperature Flexible model is superior at high temperature Thermal conductivity Thuat T. Trinh, Thijs J. H. Vlugt and Signe Kjelstrup J. Chem. Phys. 141, 134504 (2014)

16. 16 Take home messages NEMD simulations for computing thermal conductivity. Flexibility of model: important contribution to the conductivity at high temperature. CO 2 model: TraPPE ( ~ room temperature) and EMP2_Flex (T >500K)

17. 17 THANK YOU FOR YOUR ATTENTION! THANKS TO NTNU, NFR: ISP project Supercomputer