In this paper, we propose a one band tight binding model Hamiltonian for the newly discovered 122-type Selenide family of the iron-based system incorporated with the nearest-neighbor (NN) and the next-nearest-neighbor (NNN) hopping integrals $t_1$ and $t_2$, respectively. The spin–spin interactions of the electrons leading to the antiferromagnetic spin density wave (SDW) order have been studied at wave vector $Q=(\pi ,\pi ∕2)$. The electron Green’s functions are calculated from the Hamiltonian model using Green’s function technique and finally the SDW gap equation is derived and studied using their NN and NNN spin coupling $g_1$ and $g_2$, respectively.

中文翻译：

---

铁硫属化物 AxFe2−xSe2 中低能自旋激发的理论模型研究：单能带方法

在本文中，我们为新发现的铁基系统的 122 型硒化物家族提出了一种单带紧束缚模型哈密顿量，并结合了最近邻 (NN) 和次最近邻 (NNN) 跳跃积分${吨}_1$和${吨}_2$， 分别。已经在波向量处研究了导致反铁磁自旋密度波（SDW）阶的电子的自旋-自旋相互作用$问=(\pi ,\pi ∕2)$. 使用格林函数技术从哈密顿模型计算电子格林函数，最后使用它们的 NN 和 NNN 自旋耦合推导出和研究 SDW 间隙方程$G_1$和$G_2$， 分别。