**1.**

The BCS theory describes superconductivity as a microscopic effect caused by a condensation of Cooper pairs.

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The BCS theory describes superconductivity as a microscopic effect caused by a condensation of Cooper pairs.

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The BCS theory is used in nuclear physics to describe the pairing interaction between nucleons in an atomic nucleus.

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The BCS theory was first published in April 1957 in the letter, "Microscopic BCS theory of superconductivity".

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The BCS theory requires only that the potential be attractive, regardless of its origin.

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BCS theory starts from the assumption that there is some attraction between electrons, which can overcome the Coulomb repulsion.

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However, the results of BCS theory do not depend on the origin of the attractive interaction.

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The original results of BCS theory described an s-wave superconducting state, which is the rule among low-temperature superconductors but is not realized in many unconventional superconductors such as the d-wave high-temperature superconductors.

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Extensions of BCS theory exist to describe these other cases, although they are insufficient to completely describe the observed features of high-temperature superconductivity.

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BCS theory is able to give an approximation for the quantum-mechanical many-body state of the system of electrons inside the metal.

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The BCS theory formalism is based on the reduced potential for the electrons' attraction.

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BCS theory derived several important theoretical predictions that are independent of the details of the interaction, since the quantitative predictions mentioned below hold for any sufficiently weak attraction between the electrons and this last condition is fulfilled for many low temperature superconductors - the so-called weak-coupling case.

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