Abstract
The authors derive an exact sum rule satisfied by the dispersion relations of the commensurable case of Harper's equation (1955). They use this result to derive a lower bound for the total bandwidth of the spectrum and to provide a stronger analytical justification for a result due to Thouless (1990) concerning the total bandwidth when the commensurability is a high order rational.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
