An improved unrestricted Hartree–Fock UHF crystal orbital method for infinite one‐dimensional systems having antiferromagnetic spin array is presented. This variational version of the UHF method is composed of two steps of self‐consistent‐field SCF calculations. The second SCF equation is to be solved using the canonical transformation between specific crystal orbitals around the Fermi level of the first conventional SCF solution. The energy gain and the forbidden band gap (correlation gap) associated with the hypothetical antiferromagnetic state of trans‐polyacetylene are examined as an example. © 1993 John Wiley & Sons, Inc.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Physical and Theoretical Chemistry