我用castep计算一种带隙较小(大约2.0ev)材料的声子谱,方法是优化之后紧接着就算声子谱,结果出错了,优化成功了,但计算声子谱出错了,输出文件提示说“this can be caused by the system having no or very small band gap, we suggest running a bandstructure calculation to investigate.”从提示中可以看出是因为我的体系带隙太小了,那难道带细小的体系就不能算声子谱了么?求给位虫友指教一二!