# Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations

## Abstract

We report a spin-unrestricted density functional theory (DFT) solution at the symmetric dimer structure for cluster models of Si(100). With this solution, it is shown that the symmetric structure is a minimum on the DFT potential energy surface, although higher in energy than the buckled structure. In restricted DFT calculations the symmetric structure is a saddle point connecting the two buckled minima. To further assess the effects of electron correlation on the relative energies of symmetric versus buckled dimers on Si(100), multireference second order perturbation theory (MRMP2) calculations are performed on these DFT optimized minima. The symmetric structure is predicted to be lower in energy than the buckled structure via MRMP2, while the reverse order is found by DFT. The implications for recent experimental interpretations are discussed.

- Authors:

- Publication Date:

- Research Org.:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

- Sponsoring Org.:
- USDOE Director. Office of Science. Office of Basic Energy Sciences, SciDAC Computational Chemistry Program Contract DE-FG02-01ER403301 (US)

- OSTI Identifier:
- 836668

- Report Number(s):
- LBNL-53827

R&D Project: 403301; TRN: US0500772

- DOE Contract Number:
- AC03-76SF00098

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Chemical Physics

- Additional Journal Information:
- Journal Volume: 119; Journal Issue: 20; Other Information: Submitted to Journal of Chemical Physics: Volume 119, No.20; Journal Publication Date: 22 Nov 2003; PBD: 29 Aug 2003

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; CLUSTER MODEL; DIMERS; ELECTRON CORRELATION; FUNCTIONALS; PERTURBATION THEORY; POTENTIAL ENERGY; DENSITY FUNCTIONAL THEORY (DFT)

### Citation Formats

```
Jung, Yousung, Shao, Yihan, Gordon, Mark S, Doren, Douglas J, and Head-Gordon, Martin.
```*Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations*. United States: N. p., 2003.
Web. doi:10.1063/1.1620994.

```
Jung, Yousung, Shao, Yihan, Gordon, Mark S, Doren, Douglas J, & Head-Gordon, Martin.
```*Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations*. United States. doi:10.1063/1.1620994.

```
Jung, Yousung, Shao, Yihan, Gordon, Mark S, Doren, Douglas J, and Head-Gordon, Martin. Fri .
"Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations". United States. doi:10.1063/1.1620994. https://www.osti.gov/servlets/purl/836668.
```

```
@article{osti_836668,
```

title = {Are both symmetric and buckled dimers on Si(100) minima? Density functional and multireference perturbation theory calculations},

author = {Jung, Yousung and Shao, Yihan and Gordon, Mark S and Doren, Douglas J and Head-Gordon, Martin},

abstractNote = {We report a spin-unrestricted density functional theory (DFT) solution at the symmetric dimer structure for cluster models of Si(100). With this solution, it is shown that the symmetric structure is a minimum on the DFT potential energy surface, although higher in energy than the buckled structure. In restricted DFT calculations the symmetric structure is a saddle point connecting the two buckled minima. To further assess the effects of electron correlation on the relative energies of symmetric versus buckled dimers on Si(100), multireference second order perturbation theory (MRMP2) calculations are performed on these DFT optimized minima. The symmetric structure is predicted to be lower in energy than the buckled structure via MRMP2, while the reverse order is found by DFT. The implications for recent experimental interpretations are discussed.},

doi = {10.1063/1.1620994},

journal = {Journal of Chemical Physics},

number = 20,

volume = 119,

place = {United States},

year = {2003},

month = {8}

}