开壳层分子体系一般比闭壳层体系更为复杂，对高对称性分子尤其如此。其中一个重要原因是开壳层体系的对称性问题更难处理。我们将非相对论的ROHF(限制性开壳层Hartree-Fock)方法推广到相对论范畴，得到适用于开壳层分子体系的对称性匹配的相对论ROHF方法。此方法可以用于计算开壳层分子的零场分裂常数、g因子等性质，以及对称性匹配的含时密度泛函理论。

Due to symmetry reasons, open-shell systems are more difficult for quantum chemical calculations than closed shell systems. This is particularly so for molecular systems of high spin and spatial symmetries. We will generalize the non-relativistic symmetry-adapted restricted open-shell Hartree-Fock (ROHF) approach to the relativistic regime, based on which the zero-field splitting and g-factor can readily be calculated. Moreover, a symmetry-adapted open-shell time-dependent density functional theory can also be formulated.