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arXiv 1405.4199quant-phhep-lathep-thmath-phmath.MP
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格点上引力和斥力的相似性

The similarity of attractive and repulsive forces on a lattice

Marjan-S. Mirahmadi, Amir H. Fatollahi, Mohammad Khorrami

摘要:

在格子上,由于动量空间是紧的,所以动能不仅从下面有界,而且从上面也有界。它表明,这在某种程度上消除了排斥力和吸引力之间的区别。特别地,可以看出,具有吸引力的区域对于能量高于一定值的状态将是禁止的,而排斥力可以发展束缚态。一个明确的变换介绍了相应的排斥力的系统的频谱,对应于一个吸引力的类似系统。显式的数值例子中提出的离散能量的粒子受到排斥力的逐段恒定的潜力。最后,对一个一维连续体上的定常系统的参数进行了调整,使得该系统的能量类似于一维晶格上系统的动能.特别地,示出了可以调谐参数,使得当第一能带的宽度及其位置保持有限时,第一能带和下一能带之间的能隙变为无穷大,使得有效地仅第一能带是相关的。

英文摘要:

On a lattice, as the momentum space is compact, the kinetic energy is bounded not only from below but also from above. It is shown that this, somehow removes the distinction between repulsive and attractive forces. In particular, it is seen that a region with attractive force would appear forbidden for states with energies higher than a certain value, while repulsive forces could develop bound-states. An explicit transformation is introduced which transforms the spectrum of a system corresponding to a repulsive force, to that of a similar system corresponding to an attractive force. Explicit numerical examples are presented for discrete energies of bound-states of a particle experiencing repulsive force by a piecewise constant potential. Finally, the parameters of a specific one dimensional translationally invariant system on continuum are tuned so that the energy of the system resembles the kinetic energy of a system on a one dimensional lattice. In particular, it is shown that the parameters could be tuned so that while the width of the first energy band and its position are kept finite, the energy gap between the first energy band and the next energy band go to infinity, so that effectively only the first energy band is relevant.

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