Abstract
The stability of the possible ground states of an infinite linear equidistant polyene model has been discussed in the PPP approximation of the unrestricted-Hartree–Fock (UHF) method. The emphasis has been placed upon the investigation of nonsinglet (triplet) instabilities: the spin-density waves (SDW's) and the spin-bond-order alternation waves (SBAW's). For physically realistic parameter sets the SDW ground state of the infinite linear equidistant polyene has been shown to be lowest in energy. Whereas the symmetry-adapted restricted HF (RHF) solution (SAS) has been shown to be unstable to the formation of SDW's and SBAW's for all investigated parametrizations, the bond-order alternation wave (BAW) solution has been found to be unstable to the formation of SDW's, but stable to the formation of SBAW's; in fact, the BAW's and the SBAW's have been shown to yield identical gap widths and ground-state energies (at least in the PPP method). It has been shown that there exist such sets of semiempirical parameters for which the charge-density wave (CDW) ground state is nonsinglet stable irrespective of the existence of an energetically advantageous SDW solution for the same parameter set.
| Original language | Undefined/Unknown |
|---|---|
| Pages (from-to) | 367-383 |
| Number of pages | 17 |
| Journal | INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY |
| Volume | 22 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 1982 |