This document summarizes a study of the effects of solvents and ligands on the energetics and optical properties of small gold clusters. Key findings include: - Ligand binding leads to more planar and stable geometries for Au4 and Au6 clusters. - The number and type of ligands affects cluster geometries and binding energies. More ligands decrease metal-ligand binding energy. - Ligands increase transition energies and oscillator strengths compared to bare clusters. Solvation effects partially mimic ligand effects on transition energies. - Relativistic and counterpoise corrections have small effects on cluster energies and properties.

2. PBEPBE

3. TPSSTPSS

4. B3LYP

5. CAM-B3LYP

6. LANL2DZ

7. LAN2DZ+P

8. def2-SVP

9. def2-TZVP

10. def2-QZVP

11. Gaussian 03/09

12. Turbomol

13. NWChem 5.1

14. Model -CPCM

16. Ligand binding leads to the stabilization of more planar isomers of Au4 and Au6.

17. No size scaling was revealed as judged by the 1st transition energy from Au2 to Au8.

18. Increase in number of ligands around the metal core reduces the metal-ligand binding energy as expected.

19. Ligands significantly effect the cluster geometries.

20. Neutral gold clusters form stable bonds with primary and tertiary amine ligands, which is in contrast to cationic gold cluster, which are stabilized with phosphenes only.

21. Number of ligands binding to a gold cluster largely depends upon cluster geometry.

22. Basis set with Polarization functional are required to investigate small gold clusters with ligands.

23. LANL2DZ reproduces the trends with one family of ligands.

24. Ligands increase the energies and oscillator strengths of 1st transition of gold clusters.

26. Counter poise correction as well have small effect on energies (binding energy/mol).