2015/11/24 by Philip E. Hoggan, Hoggan, Philip E
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Advanced Physical and Chemical Molecular Interactions #Atomic and Molecular Physics #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · pdf · doi:10.48550/arxiv.1511.07857
openalex publication_date 2015/11/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Many chemical reactions involve bond-dissociation. This is also true for\nreactions at solid surfaces, in which the dissociation step is often limiting\nbut facilitated in comparison to gas phase reaction channels. This work\nconsiders hydrogen dissociation. Reliable molecular beam results are available\nfor this reaction at some copper surfaces. Heterogeneous catalysis by copper is\nsimulated. It was investigated in our previous work since it is in many ways a\nprototype metal presenting a close-packed surface here. These hydrogen\nmolecules are adsorbed at Cu(111) and fixed geometries on the dissociation\nreaction pathway for stretched and distant equilibrium H2 are given by using\nDensity Functional Theory (DFT) calculations in a plane wave basis. The PBE\nwave-functions at these bond-lengths serve as trial input for Quantum Monte\nCarlo (QMC) simulations of the ground states to obtain highly accurate\ncorrelated results for the associated activation barriers indicating the\ncatalytic effect on this dissociation. This correlation varies as bonds\ndissociate, requiring its accurate evaluation. Finite size effects and\nfixed-node error are possible limitations to accuracy of this type of QMC\nstudy. We are able to limit fixed node error, using certain trial\nwave-functions. The finite size effect is considerable, although comparing two\nadsorbed geometries cancels about 90% with respect to clean surfaces. The\npseudo-potential used to represent the atomic core of copper must also be\ndetermined carefully: we leave 11 active electrons but include the 3d shell in\nthe pseudo-potential.\n