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Submitted on 1 Jan 1978
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THE PAIR Π-ELECTRON CORRELATION OF THE
SUPERCONDUCTING TYPE IN THE COMPLEX
MOLECULES
V. Kresin
To cite this version:
JOURNAL DE PHYSIQUE Colloque C6, suppliment au no 8, Tome 39, aozit 1978, page ~ 6 - 4 7 9
THE P A I R II-ELECTRON CORRELATION OF THE SUPERCONDUCTING TYPE I N THE COMPLEX MOLECULES
V.Z. Kresin
Moscow Correspondance PedagogicaZ Institute, U.S.S.R.
RQsum6.- Nous considBrons les corr6lations de paires des Qlectrons n et le mdcanisme de cette corrl- lation. On peut expliquer les propridtds optiques et magndtiques de moldcules complexes par cette cor- rdlation. Nous discutons les transitions tunnel S-N dans les processus Blectrochimiques et le trans- port des Blectrons dans les membranes biologiques.
Abstract.- We consider the pair correlation of a-electrons. The mechanisms of pair correlation is dis- cussed. Optical and magnetic properties of complex molecules can be explained by this correlation. S-N tunnel transitions in the electrochemical processes and electron transfer in the biological men-
brains are discussed.
Some large molecules are characterized by the the number of a-electrons is odd.
presence of a large number of T-electrons. For exam- The pair correlation has also an important ple the aromatic compounds, the biological active effect on the magnetic properties of the large mole- molecules always contain a-electrons/l/. These col- cules since it gives rise to the observed anomalous
lectivized a-electrons move in the field of the diamagnetism of the n-electron systems. We found a-core, which is formed by the ions and by noncollec- the paramagnetic susceptibility in the direction
tivized a-electrons. perpendicular to the plane of the molecules :
a-electrons form the finite Fermi-system and their properties can be described by the methods of theory of finite ~ermi-s~stems/2/.
The present report deals with the pair correla- tion in the a-electron system. We have discussed this problem in/3/ and we are going report here some new results.
It's worth noting that the pair correlation ta- kes place in a number of Fermi systems (superconduc- tivity in the metals, pair correlation of nucleons in atomic nuclei). a-electrons and nucleons both form the finite Fermi-systems.
The pair correlation mechanisms in n-electron systems are analogous to superconducting mechanisms. This effect is due to the interaction of a-electrons with a-core. The main role play the virtual
n-u
-
electrons transitions.
What properties are due to the effect's of pair correlation ? At first, there is energy gap in the molecules, which contain even number of n-electrons. It's clear enough that a large n-electron-system should have approximately equidistant energy levels (it's a quasiclassical system). However the spectrum of the even-number a-electron-system displays a big disproportion. Namely, the energy difference between the ground state and the first excited state is much greater than this one between the first and se- cond states. The levels are equidistant only when
One can conclude that X ip'<xlp, A=O A=O
'
Van- Vleck's paramagnetism). The effects of pair corre- lation depress the paramagnetism. It leads to the anomalous diamagnetism.There following simple relation :
X I D
= yap ; y"
cF/4mc2 ,a-
the component of the-
Pelectric susceptibility in the direction lying in the plane of molecule. This relation can be verified experimentally.
Energy gap decreases in the strong magnetic field. In this case 6A % .'H Such dependence was
observed in /4/. It is worth noting that this effect should have an opposite sign in the absence of pair correlation.
Let's consider now the tunnel effects. S-N- transitions are observed in the electrochemical reactions. The oxidation of aromatic molecules re- presents the tunnel transition of n-electrons from molecule to the electrode. Thanks to the correlation effect it is possible to observe by definite volta- ge simultaneous transition of two electrons. This effect was really observed in the experiments.
The charge transfer in the biological mem- brains represents another example of tunnel effects.
We consider the movement of two T-electrons through the row of aromatic molecules, The distance between
References
molecules is definite. The pair correlation is the / l / Pullman,B., Pullman,A., Quantum Biochemistry cause of the ~ h a s e coherence in a-electron system. (Interscience, N.Y.) 1963
Such a coherence leads to the Josephson tunnel ef- /2/ Migdal,A., Theory of Finite Fermi System and Application to Atomic Nuclei (Interscience,N.Y)
fect in the biological membrains. ( 1 967)
/3/ Kresin,V., Litovchenko,V., Panasenko,A., J. Chem. Phys.,
63
(1975) 3613141 Canters,W., U a. Mol. Phys.
