Unsynchronized resonance of covalent bonds in the superconducting state

Journal of the Brazilian Chemical Society

Marconi B. S. Costa¹  Cristiano C. Bastos¹  Antonio C. Pavão¹ 

[1],Universidade Federal de Pernambuco Departamento de Química Fundamental Recife PE ,Brazil

关键词: RVB theory;    superconductivity;    DFT calculations;   

DOI  :  10.1590/S0103-50532012000700015

来源: SciELO

【 摘 要 】

DFT calculations performed on different cluster models of cuprates (LaBa2Cu3O6.7, La1.85Sr0.15CuO4, YBa2Cu3O7, TlBa2Ca2Cu3O8.78, HgBa2Ca2Cu3O8.27), metallic systems (Nb3Ge, MgB2) and the pnictide LaO0.92F0.08FeAs made evident the occurrence of unsynchronized resonance of covalent bonds in the superconducting state, as predicted by Pauling´s resonating valence bond (RVB) theory. For cuprates, the unsynchronized resonance involves electron transfer between Cu atoms accompanied by a decrease in the charge of the La, Sr, Y and Ca atoms. For MgB2, electron transfer occurs in the Mg layer, while the B layer behaves as charge reservoir. For Nb3Ge, unsynchronized resonance occurs among the Ge atoms, which should be responsible for charge transfer. For LaO0.92F0.08FeAs, the results suggest that both La-O and Fe-As layers are involved in the mechanism of superconductivity. The identification of unsynchronized resonances in these systems provides evidence which supports RVB as a suitable theory for high-temperature superconductivity (high-T C).

【 授权许可】

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