Chem3D 8.0 Manual - CambridgeSoft

Atomic Orbital Spin Density A.O.0.08375 C1 p y0.94768 C1 p zDensity computation becomes too resourceintensive for large molecules. For more informationsee the MOPAC online manual, page 28.The following table contains the keywordsautomatically sent to MOPAC and those you can useto affect this property.-0.01511 C2 SKeywordDescription-0.06345 C2 p x-0.01844 C2 p yESRAutomatically sent to MOPACto specify RHF spin densitycalculation.-0.03463 C2 p z-0.07896 H3 sGEO-OKAutomatically sent to MOPACto override checking of the Z-matrix.0.07815 H4 s0.01046 H5 s0.05488 H6 s0.05329 H7 sYou can reason from the result shown below that theunpaired electron in the ethyl radical is morelocalized at p z orbital on C1. Generally, this is agood indication of the reactive siteRHF Spin DensityRHF Spin Density uses the 1/2 electron correctionand a single configuration interaction calculation toisolate the alpha spin density in a molecule. Thismethod is particularly useful when the UHF SpinMMOKRHF Spin Density for the EthylRadicalTo calculate the RHF spin density:Automatically sent to MOPACto specify Molecular Mechanicscorrection for amide bonds. Usethe additional keyword NOMMto turn this keyword off.1. Create the ethyl radical as described in“Hyperfine Coupling Constants for the EthylRadical” on page 170.2. From the MOPAC menu, choose MinimizeEnergy.3. On the Theory tab, choose PM3 and ClosedShell (Restricted).4. On the Properties tab, choose Spin Density.Chem3D 8 Chapter 11: MOPAC Computations • 173Spin Density