Electronic Excited States of Si(100) and Organic Molecules Adsorbed on Si(100)

Abstract

The electronically excited states of the Si(100) surface and acetylene, benzene, and 9,10-phenanthrenequinone adsorbed on Si(100) are studied with time-dependent density functional theory. The computational cost of these calculations can be reduced through truncation of the single excitation space. This allows larger cluster models of the surface in conjunction with large adsorbates to be studied. On clean Si(100), the low-lying excitations correspond to transitions between the π orbitals of the silicon-silicon dimers. These excitations are predicted to occur in the range 0.4-2 eV. When organic molecules are adsorbed on the surface, surface f molecule, molecule f surface, and electronic excitations localized within the adsorbate are also observed at higher energies. For acetylene and benzene, the remaining ππ* excitations are found to lie at lower energies than in the corresponding gas-phase species. Even though the aromaticity of 9,10-phenanthrenequinone is retained, significant shifts in the ππ* excitations of the aromatic rings are predicted. This is in part due to structural changes that occur upon adsorption.

Time dependent density functional theory study of the near-edge x-ray absorption fine structure of benzene in gas phase and on metal surfaces

“…We have used this approach to study the NEXAFS ͑Ref. 10͒ and electronic 29,30 spectroscopy of a variety of molecules adsorbed on surfaces.…”

Excited States from Time‐Dependent Density Functional Theory

“…Another major area of application of TDDFT involves clusters, large and small, covalent and metallic, and everything in between, [93][94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112] as, for example, Met-Cars. 113 Several studies include solvent effects, [114][115][116][117][118][119][120][121][122] one example being the behavior of metal ions in explicit water.…”

Polymer adhesion: First-principles calculations of the adsorption of organic molecules onto Si surfaces

“…[1][2][3] An additional motivation for studying these systems is to understand the nature of adhesion between plastics and metal or ceramic surfaces. Many of these materials do not adhere well and the main focus of this research is to obtain a better understanding of the structure and bonding at the polymer-surface interface.…”

“…The adsorption of organic molecules on semi-conductor surfaces is of increasing importance to industry due to interest in the development of organic optoelectronic devices, micro/molecular-scale electronics and biofunctionality [1,2,3]. An additional motivation for studying these systems is to understand the nature of adhesion between plastics and metal or ceramic surfaces.…”