By employing a pseudoorthonormal coordinate-free approach, the Dirac equation for particles in the Kerr–Newman spacetime is separated into its radial and angular parts. In the massless case to which a special attention is given, the general Heun-type equations turn into their confluent form. We show how one recovers some results previously obtained in literature, by other means.

中文翻译：

---

Kerr-Newman时空和Heun函数的Dirac方程

通过采用伪正交的无坐标方法，将Kerr-Newman时空中的粒子的Dirac方程分为径向部分和角度部分。在特别注意的无质量情况下，一般的Heun型方程变成它们的合流形式。我们展示了如何通过其他方法来恢复以前在文献中获得的一些结果。