Using first-principles calculations, we investigated the magnetic and optical properties of monolayer 2H VSe₂ and VSSe. We obtained a direct band gap of 1.04 eV in pristine 2H VSe₂ and 1.05 eV for the Janus VSSe layer. Both systems displayed a ferromagnetic ground state. We also found an in-plane magnetic anisotropy, and the calculated in-plane magnetic anisotropy energies were 1.09 meV in VSe2 and 0.69 meV. The major contribution to the magnetic moment originated from the V atom. However, the Se atom induced strong in-plane anisotropy, not the V atom. The contribution to the magnetic anisotropy from the Se atom was almost twice larger than that from the V atom. Through the frequency-dependent dielectric function, we obtained the refractive index of ~ 2.5 in the visible range. Besides, we also found that the reflectivity was less than 0.2 in both structures at the visible range. This indicates the optically transparent in the visible frequencies.

_{使用第一性原理计算，我们研究了单层 2H VSe 2}和 VSSe的磁性和光学性质。_{我们在原始 2H VSe 2}中获得了 1.04 eV 的直接带隙Janus VSSe 层为 1.05 eV。两个系统都显示出铁磁基态。我们还发现了面内磁各向异性，计算出的面内磁各向异性能量为 VSe2 中的 1.09 meV 和 0.69 meV。对磁矩的主要贡献来自 V 原子。然而，Se 原子引起了强烈的面内各向异性，而不是 V 原子。Se原子对磁各向异性的贡献几乎是V原子的两倍。通过频率相关的介电函数，我们在可见光范围内获得了~2.5的折射率。此外，我们还发现两种结构在可见光范围内的反射率均小于0.2。这表明在可见频率中是光学透明的。