Dhar A, Shastry BS, Dasgupta C
Physics Department, Indian Institute of Science, Bangalore 560012, India.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Aug;62(2 Pt A):1592-600. doi: 10.1103/physreve.62.1592.
We study the equilibrium and dynamical properties of the axial next-nearest-neighbor Ising chain at the multiphase point. An interesting property of the system is the macroscopic degeneracy of the ground state leading to finite zero-temperature entropy. In our equilibrium study we consider the effect of softening the spins. We show that the degeneracy of the ground state is lifted and there is a qualitative change in the low-temperature behavior of the system with a well-defined low-temperature peak of the specific heat that carries the thermodynamic "weight" of the ground state entropy. In our study of the dynamical properties, the stochastic Kawasaki dynamics is considered. The Fokker-Planck operator for the process corresponds to a quantum spin Hamiltonian similar to the Heisenberg ferromagnet but with constraints on allowed states. This leads to a number of differences in its properties, which are obtained through exact numerical diagonalization, simulations, and by obtaining various analytic bounds.
我们研究了多相点处轴向次近邻伊辛链的平衡和动力学性质。该系统的一个有趣性质是基态的宏观简并性导致有限的零温熵。在我们的平衡研究中，我们考虑了自旋软化的影响。我们表明，基态的简并性被消除，并且系统的低温行为发生了质的变化，比热在低温下有一个明确的峰值，该峰值承载了基态熵的热力学“权重”。在我们对动力学性质的研究中，考虑了随机川崎动力学。该过程的福克 - 普朗克算符对应于一个类似于海森堡铁磁体的量子自旋哈密顿量，但对允许状态有约束。这导致了其性质上的一些差异，这些差异是通过精确的数值对角化、模拟以及获得各种解析界得到的。
