Heisenberg coupling constant predicted for molecular magnets with pairwise spin-contamination correction

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:396

Article

Masunov, Artem E.^1,2,3  Gangopadhyay, Shruba^4,5 

[1] Univ Cent Florida, Dept Chem, NanoSci Technol Ctr, Orlando, FL 32326 USA

[2] Univ Cent Florida, Dept Phys, Orlando, FL 32326 USA

[3] RAS, Photochem Ctr, Moscow 119421, Russia

[4] Univ Calif Davis, Dept Phys, Davis, CA 95616 USA

[5] IBM Almaden Res Ctr, San Jose, CA 95120 USA

关键词: Density functional theory;    High spin ground state;    Molecular magnet;   

DOI  :  10.1016/j.jmmm.2015.07.117

来源: Elsevier

【 摘 要 】

New method to eliminate the spin-contamination in broken symmetry density functional theory (BS DFT) calculations is introduced. Unlike conventional spin-purification COffection, this method is based on canonical Natural Orbitals (NO) for each high/low spin coupled electron pair. We derive an expression to extract the energy of the pure singlet state given in tel of energy of BS DFT solution, the occupation number of the bonding NO, and the energy of the higher spin state built on these bonding and antibonding NOs (not self-consistent Kohn-Sham orbitals of the high spin state). Compared to the other spin-contamination correction schemes, spin-correction is applied to each correlated electron pair individually. We investigate two binuclear Mn(IV) molecular magnets using this pairwise correction. While one of the molecules is described by magnetic orbitals strongly localized on the metal centers, and spin gap is accurately predicted by Noodleman and Yamaguchi schemes, for the other one the gap is predicted poorly by these schemes due to strong delocalization of the magnetic orbitals onto the ligands. We show our new correction to yield more accurate results in both cases. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

Free