A mechanism of disappearance and formation of the Efimov levels of the helium ^4He trimer is studied when the force of the interatomic interaction is changed. It is shown that these levels arise from virtual levels which are in turn formed from (quasi)resonances settled on the real axis. The resonances including virtual levels are calculated by the method based on the solution of the boundary value problem, at complex energies, for the Faddeev differential equations describing the scattering processes (2+1\to 2+1; 1+1+1). All the calculations are performed with the known interatomic Aziz He-He potential HFD-B. A very strong repulsive component of this potential at short distances between helium atoms is approximated by a hard core. A special attention is paid to the substantiation of the method used for computing resonances and to the investigation of its applicability range.
Supersymmetric isospectral formalism for the calculation of near-zero energy states: application to the very weakly bound ${^4}$He trimer excited state
Benchmark helium dimer and trimer calculations with a public few-body code
我们提出了详细的计算的束缚态和散射态的二聚体和三聚体的他产生高度准确的数据和测试的非相对论性三体代码目前正在开发的公共分配。对于这些系统，在出版的作品中经常使用的基本常数的不确定性和不准确性可以大大超过数值误差。我们的基准计算包括计算的数值精度的具体估计，并探讨基本常数及其不确定性的敏感性。在以前的计算中使用不精确的耦合常数导致基态能量的0.08%的误差，激发态能量的0.3%的误差和高达0.15%的误差的原子二聚体散射长度在三个$^4$ He原子的系统。对于非对称的$^{4}$ He $_{2}^{3}$ He系统，计算的束缚态能量和原子-二聚体散射长度的误差分别为0.3%和0.03%。
