A general method to obtain well localized Wannier functions for composite energy bands in linear combination of atomic orbital periodic calculations

2001 ◽  
Vol 115 (21) ◽  
pp. 9708-9719 ◽  
Author(s):  
Claudio M. Zicovich-Wilson ◽  
Roberto Dovesi ◽  
Victor R. Saunders
1997 ◽  
Vol 56 (20) ◽  
pp. 12847-12865 ◽  
Author(s):  
Nicola Marzari ◽  
David Vanderbilt

1970 ◽  
Vol 48 (20) ◽  
pp. 3154-3163 ◽  
Author(s):  
François Tonnard ◽  
Simone Odiot ◽  
Maryvonne L. Martin

A relation between the diamagnetic term for a proton bonded to a carbon atom and the linear combination of atomic orbital charges on C and H is established. Proton diamagnetic terms of some vinyl ethers are calculated, and the conformation of ethoxy group in these molecules studied.


2001 ◽  
Vol 65 (3) ◽  
Author(s):  
Ivo Souza ◽  
Nicola Marzari ◽  
David Vanderbilt

Author(s):  
Ekkehard Krüger

As shown in former papers, the nonadiabatic Heisenberg model presents a novel mechanism of Cooper pair formation generated by the strongly correlated atomic-like motion of the electrons in narrow, roughly half-filled "superconducting bands". These are energy bands represented by optimally localized spin-dependent Wannier functions adapted to the symmetry of the material under consideration. The formation of Cooper pairs is not the result of an attractive electron-electron interaction but can be described in terms of quantum mechanical constraining forces constraining the electrons to form Cooper pairs. There is theoretical and experimental evidence that only this nonadiabatic mechanism operating in superconducting bands may produce eigenstates in which the electrons form Cooper pairs. These constraining forces stabilize the Cooper pairs in any superconductor, whether conventional or unconventional. Here we report evidence that also the experimentally found superconducting state in bismuth at ambient as well as at high pressure is connected with a narrow, roughly half-filled superconducting band in the respective band structure. This observation corroborates once more the significance of constraining forces in the theory of superconductivity.


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