Berlin 2018 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 78: Hybrid and Perovskite Photovoltaics II
CPP 78.5: Talk
Friday, March 16, 2018, 10:30–10:45, C 264
Assessing density functionals using many body theory for hybrid perovskites — •Menno Bokdam, Jonathan Lahnsteiner, Benjamin Ramberger, Tobias Schäfer, and Georg Kresse — University of Vienna, Faculty of Physics and Center for Computational Materials Sciences, Vienna, Austria
Which density functional is the "best" for structure simulations of a particular material? A concise, first principles, approach to answer this question is presented. The random phase approximation (RPA)— an accurate many body theory— is used to evaluate various density functionals.[1] To demonstrate and verify the method, we apply it to the hybrid perovskite MAPbI3, a promising new solar cell material. The evaluation is done by first creating finite temperature ensembles for small supercells using RPA molecular dynamics, and then evaluating the variance between the RPA and various approximate density functionals for these ensembles. We find that, contrary to recent suggestions, van der Waals functionals do not improve the description of the material, whereas hybrid functionals and the SCAN (strongly constrained appropriately normed) density functional yield very good agreement with the RPA. Finally, our study shows that in the room temperature tetragonal phase of MAPbI3, the molecules are preferentially parallel to the shorter lattice vectors but reorientation on ps time scales is still possible.
[1] Bokdam et. al., Phys. Rev. Lett. 119, 145501 (2017)