### Abstract

Results of electronic structure calculations of C_{60} and M_{3}C_{60} (M = K, Rb, Cs) fcc crystals carried out by the full-potential linear muffin-tin orbital (LMTO) method are reported. Undoped C_{60} is found to be semiconducting with a direct gap between the fully occupied valence band and empty conduction band of 0.75 eV at the X-point. The Fermi level in M_{3}C_{60} falls on the half-occupied peak formed mainly by the 2p states of the closest carbon atoms with neighboring C_{60} molecules. Estimates of electron-phonon coupling using the crude rigid iron approximation give δ values of 0.51, 0.61 and 0.72 for K, Rb, and Cs doping, respectively. using an average phonon frequency of 1100 K the McMillan formula gives T_{c} values of 16 K for K_{3}C_{60}, 30K for Rb_{3}C_{60} and 47 K for Cs_{3}C_{60}. The calculated T_{c} values for K and Rb doping are in very good agreement with experiment and the predicted T_{c} value of Cs_{3}C_{60} is close to the value obtained by linear extrapolations based on the lattice constant. These are the first calculated results for δ and T_{c} and they strongly support the idea that BCS superconductivity is caused by the electron-phonon interaction and that T_{c} changes are caused by negative chemical pressures effects resulting in the increase of lattice constants in the K, Rb, and Cs series.

Original language | English |
---|---|

Pages (from-to) | 399-408 |

Number of pages | 10 |

Journal | Physica C: Superconductivity and its Applications |

Volume | 191 |

Issue number | 3-4 |

DOIs | |

Publication status | Published - Feb 15 1992 |

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### ASJC Scopus subject areas

- Condensed Matter Physics

### Cite this

_{3}C

_{60}, Rb

_{3}C

_{60}and Cs

_{3}C

_{60}.

*Physica C: Superconductivity and its Applications*,

*191*(3-4), 399-408. https://doi.org/10.1016/0921-4534(92)90936-7

**Electronic structure, electron-phonon interaction and superconductivity in K _{3}C_{60}, Rb_{3}C_{60} and Cs_{3}C_{60}.** / Novikov, D. L.; Gubanov, V. A.; Freeman, Arthur J.

Research output: Contribution to journal › Article

_{3}C

_{60}, Rb

_{3}C

_{60}and Cs

_{3}C

_{60}',

*Physica C: Superconductivity and its Applications*, vol. 191, no. 3-4, pp. 399-408. https://doi.org/10.1016/0921-4534(92)90936-7

_{3}C

_{60}, Rb

_{3}C

_{60}and Cs

_{3}C

_{60}. Physica C: Superconductivity and its Applications. 1992 Feb 15;191(3-4):399-408. https://doi.org/10.1016/0921-4534(92)90936-7

}

TY - JOUR

T1 - Electronic structure, electron-phonon interaction and superconductivity in K3C60, Rb3C60 and Cs3C60

AU - Novikov, D. L.

AU - Gubanov, V. A.

AU - Freeman, Arthur J

PY - 1992/2/15

Y1 - 1992/2/15

N2 - Results of electronic structure calculations of C60 and M3C60 (M = K, Rb, Cs) fcc crystals carried out by the full-potential linear muffin-tin orbital (LMTO) method are reported. Undoped C60 is found to be semiconducting with a direct gap between the fully occupied valence band and empty conduction band of 0.75 eV at the X-point. The Fermi level in M3C60 falls on the half-occupied peak formed mainly by the 2p states of the closest carbon atoms with neighboring C60 molecules. Estimates of electron-phonon coupling using the crude rigid iron approximation give δ values of 0.51, 0.61 and 0.72 for K, Rb, and Cs doping, respectively. using an average phonon frequency of 1100 K the McMillan formula gives Tc values of 16 K for K3C60, 30K for Rb3C60 and 47 K for Cs3C60. The calculated Tc values for K and Rb doping are in very good agreement with experiment and the predicted Tc value of Cs3C60 is close to the value obtained by linear extrapolations based on the lattice constant. These are the first calculated results for δ and Tc and they strongly support the idea that BCS superconductivity is caused by the electron-phonon interaction and that Tc changes are caused by negative chemical pressures effects resulting in the increase of lattice constants in the K, Rb, and Cs series.

AB - Results of electronic structure calculations of C60 and M3C60 (M = K, Rb, Cs) fcc crystals carried out by the full-potential linear muffin-tin orbital (LMTO) method are reported. Undoped C60 is found to be semiconducting with a direct gap between the fully occupied valence band and empty conduction band of 0.75 eV at the X-point. The Fermi level in M3C60 falls on the half-occupied peak formed mainly by the 2p states of the closest carbon atoms with neighboring C60 molecules. Estimates of electron-phonon coupling using the crude rigid iron approximation give δ values of 0.51, 0.61 and 0.72 for K, Rb, and Cs doping, respectively. using an average phonon frequency of 1100 K the McMillan formula gives Tc values of 16 K for K3C60, 30K for Rb3C60 and 47 K for Cs3C60. The calculated Tc values for K and Rb doping are in very good agreement with experiment and the predicted Tc value of Cs3C60 is close to the value obtained by linear extrapolations based on the lattice constant. These are the first calculated results for δ and Tc and they strongly support the idea that BCS superconductivity is caused by the electron-phonon interaction and that Tc changes are caused by negative chemical pressures effects resulting in the increase of lattice constants in the K, Rb, and Cs series.

UR - http://www.scopus.com/inward/record.url?scp=0026818648&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0026818648&partnerID=8YFLogxK

U2 - 10.1016/0921-4534(92)90936-7

DO - 10.1016/0921-4534(92)90936-7

M3 - Article

VL - 191

SP - 399

EP - 408

JO - Physica C: Superconductivity and its Applications

JF - Physica C: Superconductivity and its Applications

SN - 0921-4534

IS - 3-4

ER -