Antiferromagnetic spin couplings in cyclobutadiene chains

Journal of Physical Chemistry B

Volumn 101, Issue 34, 1997, Pages 6688-6691

  Raos, Guido ^a   McNicholas, Stuart J ^b   Gerratt, Joseph ^b   Cooper, David L ^c   Karadakov, Peter B ^d  

^a POLITECNICO DI MILANO   (Italy)

^b UNIVERSITY OF BRISTOL   (United Kingdom)

^c UNIVERSITY OF LIVERPOOL   (United Kingdom)

^d UNIVERSITY OF SURREY   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

ANTIFERROMAGNETISM; CALCULATIONS; ELECTRON ENERGY LEVELS; ELECTRONIC STRUCTURE; MONOMERS; NUMERICAL METHODS; OLIGOMERS;

DIMETHYLENOPOLYCYCLOBUTADIENE; SPIN COUPLED METHOD; SPIN MULTIPLICITY;

HYDROCARBONS;

EID: 0031211157     PISSN: 15206106     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp971345f     Document Type: Article

References (35)

1. Miller, J. S.; Epstein, A. J. Ange. Chem. Int. Ed. 1994, 33, 385.
2. Longuet-Higgins, H. C. J. Chem. Phys. 1950, 18, 265.
3. Borden, W. T.; Davidson, E. R. J. Am. Chem. Soc. 1977, 99, 4587.
4. Ovchinnikov, A. A. Theor. Chim. Acta 1978, 47, 297.
5. (a) Klein, D. J. J. Chem. Phys. 1982, 77, 3098.
6. (b) Klein, D. J.; Nelin, C. J.; Alexander, S.; Matsen, F. A. J. Chem. Phys. 1982, 77, 3101.
7. (c) Alexander, S.; Klein, D. J. J. Am. Chem. Soc. 1988, 110, 3401.
8. Radhakrishnan, T. P. Chem. Phys. Lett. 1991, 181, 455.
9. Snyder, G. J.; Dougherty, D. A. J. Am. Chem. Soc. 1989, 111, 3927.
10. Davidson, E. R.; Borden, W. T.; Smith, J. J. Am. Chem. Soc. 1978, 100, 3299.
11. Du, P.; Hrovat, D. A.; Borden, W. T. J. Am. Chem. Soc. 1989, 111, 3773.
12. Wright, S. C.; Cooper, D. L.; Gerratt, J.; Raimondi, M. J. Chem. Soc., Chem. Commun 1989, 1489.
13. Wrigh, S. C.; Cooper, D. L.; Gerratt, J.; Raimondi, M. J. Phys. Chem. 1992, 96, 7943.
14. Pranata, J.; Dougherty, D. A. J. Am. Chem. Soc. 1987, 109, 1621.
15. Prasad, B. L. V.; Radhakrishnan, T. P. J. Phys. Chem. 1992, 96, 9232.
16. Raos, G.; Gerratt, J.; Cooper, D. L.; Raimondi, M. Chem. Phys. 1994, 186, 251.
17. Dannenberg, J. J.; Liotard, D.; Halvick, P.; Rayez, J. C. J. Phys. Chem. 1996, 100, 9631.
18. Cooper, D. I.; Gerratt, J.; Raimondi, M. Adv. Chem. Phys. 1987, 69, 319.
19. Cooper, D. L.; Gerratt, J.; Raimondi, M. Chem. Rev. 1991, 91, 929.
20. Pure triplet coupling would allow some linear invariance which could be used to localize the orbitals in the antipair.
21. (a) Feller, D.; Davidson, E. R.; Borden, W. T. J. Am. Chem. Soc. 1982, 104, 1216.
22. (b) Budzelaar, P. H. M.; Kraka, E.; Cremer, D.; Schleyer, P. v. R. J. Am. Chem. Soc. 1986, 108, 561.
23. (c) Snyder, G. J.; Dougherty, D. A. J. Am. Chem. Soc. 1989, 111, 3942.
24. Anderson, P. W. Solid State Phys. 1963, 14, 99.
25. Hehre, W. J.; Radom, L.; Schleyer, P. v. R.; Pople, J. A. Ab Initio Molecular Orbital Theory; Wiley: New York, 1986.
26. Karadakov, P. B.; Gerratt, J.; Cooper, D. L.; Raimondi, M. J. Chem. Phys. 1992, 97, 7637.
27. S. J. McNicholas, Ph.D. Thesis, University of Bristol, in preparation.
28. Maynau, D.; Said, M.; Malrieu, J. P. J. Am. Chem. Soc. 1983, 105, 5244.
29. Kuwajima, S. J. Am. Chem. Soc. 1984, 106, 6496.
30. Raos, G.; Gerrat, J.; Cooper, D. L.; Raimondi, M. Chem. Phys. 1994, 186, 233.
31. 25
32. Szabo, A.; Ostlund, N. S. Modern Quantum Chemistry, 1st ed., revised; McGraw-Hill: New York, 1989.
33. D. J. Klein and S. A. Alexander [Mol. Cryst. Liq. Cryst. 1993, 232, 219] have examined in some detail the size- or N -dependence of the singlet - triplet splitting of a model biradical. They show that the correlation correction to the "Hund's-rule-favoring" RHF splitting vanishes in the large-N limit, if doubly-excited CI is adopted in place of a size-extensive method. More generally, they argue that any truncated CI expansion, although acceptable for a small system, artificially switches over to Hund's rule prediction for larger systems.
34. We have confined our discussion mainly to the properties of the eigenstates of the Hamiltonian (or their approximations). However, particularly in the case of the polymer, it is also important to take into account the role of temperature: this produces mixing of the ground and of the excited states. In a one-dimensional system, for any "reasonable" form of the Hamiltonian, there can be no phase transition to a low-entropy ordered state (i.e., to any sort of magnetic phase). This is a general statistical mechanical theorem: see for example ref 31.
35. Huang, K. Statistical Mechanics, 2nd ed.; Wiley: New York, 1987.