Spin-oscillator model for the unzipping of biomolecules by mechanical force Articles uri icon

publication date

  • August 2012

issue

  • 2 (021919)

volume

  • 86

international standard serial number (ISSN)

  • 1539-3755

electronic international standard serial number (EISSN)

  • 1550-2376

abstract

  • A spin-oscillator system models unzipping of biomolecules (such as DNA, RNA, or proteins) subject to an external force. The system comprises a macroscopic degree of freedom, represented by a one-dimensional oscillator, and internal degrees of freedom, represented by Glauber spins with nearest-neighbor interaction and a coupling constant proportional to the oscillator position. At a critical value F-c of an applied external force F, the oscillator rest position (order parameter) changes abruptly and the system undergoes a first-order phase transition. When the external force is cycled at different rates, the extension given by the oscillator position exhibits a hysteresis cycle at high loading rates, whereas it moves reversibly over the equilibrium force-extension curve at very low loading rates. Under constant force, the logarithm of the residence time at the stable and metastable oscillator rest position is proportional to F - F-c as in an Arrhenius law.