Numerical evidence of conformal phase transition in graphene with long-range interactions
Numerical evidence of conformal phase transition in graphene with long-range interactions
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DOI：
10.1103/physrevb.99.205434
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发表时间：
2019-05-28
影响因子：
3.7
通讯作者：
von Smekal, Lorenz
中科院分区：
文献类型：
--
作者：
Buividovich, Pavel;Smith, Dominik;von Smekal, Lorenz
使用最先进的混合蒙特卡罗（HMC）模拟，我们进行了一个无偏的研究自旋密度波（SDW）和电荷密度波（CDW）之间的竞争秩序悬浮石墨烯。我们确定石墨烯的实际电子间势必须放大约1.6倍才能诱导半金属-SDW相变，并且没有发现CDW有序的证据。临界性质的研究表明，普适类的三维手征海森堡Gross-Neveu模型与两个费米子口味，预测重整化群研究和强耦合展开，是不太可能适用于这种转变。我们建议，我们的结果，而不是有利于共形相变方面的解释。此外，我们描述了一个变种的HMC算法，它使用精确的费米子力在分子动力学轨迹，避免使用赝费米子。与标准HMC相比，这允许积分器步长的大幅增加，同时实现可比较的大都会接受率，并导致相当大的性能改善。
Using state of the art Hybrid Monte Carlo (HMC) simulations we carry out an unbiased study of the competition between spin-density wave (SDW) and charge-density wave (CDW) order in suspended graphene. We determine that the realistic interelectron potential of graphene must be scaled up by a factor of roughly 1.6 to induce a semimetal-SDW phase transition and find no evidence for CDW order. A study of critical properties suggests that the universality class of the three-dimensional chiral Heisenberg Gross-Neveu model with two fermion flavors, predicted by renormalization group studies and strong-coupling expansion, is unlikely to apply to this transition. We propose that our results instead favor an interpretation in terms of a conformal phase transition. In addition, we describe a variant of the HMC algorithm which uses exact fermionic forces during molecular dynamics trajectories and avoids the use of pseudofermions. Compared to standard HMC, this allows for a substantial increase of the integrator step size while achieving comparable Metropolis acceptance rates and leads to a sizable performance improvement.