@article{kokh_buenker_liebermann_whitten_2007, title={Theoretical study of the photoinduced C-H bond cleavage in formaldehyde adsorbed on the Ag(111) surface}, volume={111}, ISSN={["1932-7455"]}, DOI={10.1021/jp071334e}, abstractNote={A theoretical study of the photoinduced C-H bond cleavage in H 2 CO adsorbed on Ag(111) surface is carried out by employing an ab initio embedding approach and multireference configuration interaction method. Pathways for one- and two-step fragmentation into CO + 2H are investigated as well as adsorption properties of the H and HCO products. The π* electron-attachment state, H 2 CO -(a) , formed due to photoinduced electron transfer from the surface to an adsorbate, serves as intermediate for the dissociation process. An effective reaction pathway includes initial nuclear relaxation of the H 2 CO -(a) anion followed by electron detachment and subsequent dissociation of the neutral H 2 CO (a) molecule. The present calculations also show that, in contrast to gaseous H 2 CO, cleavage of the C-H bond in adsorbed H 2 CO needs higher excitation energy than the C-O bond. The corresponding energy difference is obtained to be about 1.6 eV.}, number={27}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Kokh, Daria B. and Buenker, Robert J. and Liebermann, Heinz-Peter and Whitten, Jerry L.}, year={2007}, month={Jul}, pages={9914–9918} }
 @article{kokh_buenker_whitten_2006, title={Trends in adsorption of open-shell atoms and small molecular fragments on the Ag(111) surface}, volume={600}, ISSN={["1879-2758"]}, DOI={10.1016/j.susc.2006.08.032}, abstractNote={The chemisorption of various atoms (C, N, O, Cl) and molecular fragments (OH, NH, CH, NH2, CH2) on the Ag(1 1 1) surface has been studied by employing the embedded cluster and multireference single- and double-excitation configuration interaction (MRD-CI) methods. Ground and excited states of the cluster–adsorbate systems have been computed and molecular orbitals (MOs) as well as electronic charge density distributions and Mulliken populations have been analyzed in order to extract general trends in chemisorption properties for different adsorbates. It has been found that the adsorbate–surface bond is energetically most favorable when a maximum of two electrons of the metal are shared with a given adsorbate. As a result atomic/molecular fragments with less than six valence electrons (N, CH, C) retain some open shells upon adsorption, whereas oxygen as well as chlorine isovalent species form a singlet ground state on the surface. All species considered except for Cl have mainly covalent bonding character to the surface, with an electronic charge of up to 1.0 transferred to the adsorbate from the silver cluster. It has been shown that the ionicity of the bond is strongly correlated with the electron affinity of the adsorbed species. Binding energies, equilibrium geometry and adsorbate location on the cluster have been computed and compared with available experimental data. In addition, the characteristic properties of chemisorption on Ag(1 1 1) and Pt(1 1 1) surfaces have been compared.}, number={23}, journal={SURFACE SCIENCE}, author={Kokh, Daria B. and Buenker, Robert J. and Whitten, Jerry L.}, year={2006}, month={Dec}, pages={5104–5113} }
 @article{buenker_alekseyev_liebermann_lingott_hirsch_1998, title={Comparison of spin-orbit configuration interaction methods employing relativistic effective core potentials for the calculation of zero-field splittings of heavy atoms with a P-2(o) ground state}, volume={108}, ISSN={["0021-9606"]}, DOI={10.1063/1.475739}, abstractNote={Computational strategies for the treatment of relativistic effects including spin-orbit coupling at a highly correlated level are compared for a number of heavy atoms: indium, iodine, thallium, and astatine. Initial tests with perturbation theory emphasize the importance of high-energy singly excited configurations which possess large spin-orbit matrix elements with the ground state. A contracted basis consisting of L–S CI eigenfunctions (LSC–SO–CI) is found to give an accurate representation of both spin-perturbed 2Po components as long as key np→pi* singly excited configurations are included. Comparison is made with a more extensive treatment in which all selected configurations of various L–S symmetries form the basis for the multireference–spin-orbit–configuration interaction (MR–SO–CI). Good agreement is obtained with experimental SO splittings for the In, I, and At atoms at a variety of levels of treatment, indicating that the L–S contracted SO–CI approach can be implemented quite effectively with relativistic effective core potentials (RECPs) for both very electronegative atoms and also for lighter electropositive elements up through the fifth row of the periodic table. The thallium atom SO splitting is more difficult to obtain accurately because of greater differences between its valence p1/2 and p3/2 spinors than in the other cases studied, but good results are also possible with the contracted SO–CI approach in this instance, provided proper care is given to the inclusion of key singly excited L–S states. The relationship between all-electron two-component SO–CI treatments and those employing RECPs is also analyzed, and it is concluded that triply excited configurations relative to the 2Po ground state are far less important than previously reported.}, number={9}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Buenker, RJ and Alekseyev, AB and Liebermann, HP and Lingott, R and Hirsch, G}, year={1998}, month={Mar}, pages={3400–3408} }