(509h) A Mercury Adsorption Study on Fixed and Relaxed Cao Surfaces Using Density Functional Methods

The binding of Hg, HgCl, and HgCl2 to a relaxed CaO (0 0 1) surface was investigated with Density Functional Theory (DFT) methods and the results are compared with the fixed cluster results. The CaO surface was modeled with a 4x4x2 cluster, 5x5x2 cluster and a periodic slab. Structures were optimized with the Perdew-Wang(PWC) local functional with LDA using the Harris approximation in order to reduce the computational time. Adsorption energies of Hg, HgCl, and HgCl2 binding to the CaO surface were calculated by the gradient corrected (GGA) method with the BLYP functional with the lower level optimized structure. The results from each method lead to slightly different bond lengths and significantly different adsorption energies between the fixed cluster and relaxed surface when surface rumpling is permitted.