(38f) Assessing the Reliability of Calculated Catalytic Ammonia Synthesis Rates with Beef-Vdw

Authors: 
Medford, A., SLAC National Accelerator Laboratory
Wellendorff, J., SLAC National Accelerator Laboratory
Vojvodic, A., Stanford U. & SLAC National Accelerator Laboratory
Studt, F., SLAC National Accelerator Laboratory
Abild-Pedersen, F., SLAC National Accelerator Laboratory
Bligaard, T., SLAC National Accelerator Laboratory
Norskov, J. K., SUNCAT Center for Interface Science and Catalysis, Stanford University and SLAC National Accelerator Laboratory

Using a general method for estimating the exchange-correlation uncertainty in density functional theory calculations we estimate the uncertainty on catalytic rate of ammonia synthesis over a range of transition metal catalysts. In general the estimated error is significantly reduced due to correlations in the error between various intermediates and surfaces, highlighting the need for systematic methods of error estimation. Uncertainties are shown to be a complex function of reaction condition and catalyst material, and we demonstrate that relative rates between different catalysts are better described than the absolute rates. A new approach is introduced where catalysts can be screened based on the probability that their rate will be an improvement over a given standard, rather than on the basis of absolute predicted rates. The implications and challenges of analyzing sources of uncertainty beyound exchange-correltaion energy are discussed, along with the potential opportunities for application of the probabilistic approach to other areas of computational materials design.
Topics: