Multiplets in a ligand field are treated within total-energy density-functional calculations by imposing density-matrix constraints on the d-orbital occupation numbers consistent with the local site and state symmetries. We demonstrate the utility of this approach for the case of isolated Fe phthalocyanine (FePc) molecules with overall D 4h symmetry: We find three stationary states of 3E g, 3A 2g, and 3B 2g symmetries of the Fe2 + ion, and total-energy calculations clearly demonstrate that the ground state is 3A 2g. By contrast, a columnar stacking of the FePc molecules (α-FePc) is found to change the ground state to 3E g due to hybridization between adjacent molecules.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jun 18 2012|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics