Lu Bing-Nan, Li Ning, Elhatisari Serdar, Ma Yuan-Zhuo, Lee Dean, Meißner Ulf-G
Graduate School of China Academy of Engineering Physics, Beijing 100193, China.
School of Physics, Sun Yat-Sen University, Guangzhou 510275, China.
Phys Rev Lett. 2022 Jun 17;128(24):242501. doi: 10.1103/PhysRevLett.128.242501.
While first order perturbation theory is routinely used in quantum Monte Carlo (QMC) calculations, higher-order terms present significant numerical challenges. We present a new approach for computing perturbative corrections in projection QMC calculations. We demonstrate the method by computing nuclear ground state energies up to second order for a realistic chiral interaction. We calculate the binding energies of several light nuclei up to ^{16}O by expanding the Hamiltonian around the Wigner SU(4) limit and find good agreement with data. In contrast to the natural ordering of the perturbative series, we find remarkably large second-order energy corrections. This occurs because the perturbing interactions break the symmetries of the unperturbed Hamiltonian. Our method is free from the sign problem and can be applied to QMC calculations for many-body systems in nuclear physics, condensed matter physics, ultracold atoms, and quantum chemistry.
虽然一阶微扰理论在量子蒙特卡罗（QMC）计算中经常被使用，但高阶项带来了重大的数值挑战。我们提出了一种在投影QMC计算中计算微扰修正的新方法。我们通过计算现实手征相互作用下直至二阶的原子核基态能量来演示该方法。我们通过围绕维格纳SU(4)极限展开哈密顿量，计算了直至(^{16}O)的几个轻核的结合能，并与数据取得了良好的一致性。与微扰级数的自然顺序相反，我们发现二阶能量修正非常大。这是因为微扰相互作用破坏了未微扰哈密顿量的对称性。我们的方法没有符号问题，可应用于核物理、凝聚态物理、超冷原子和量子化学中多体系统的QMC计算。
