Hi, According to “funct.f90” there are two descriptions (exchange and gradient correction on exchange) for pb0x keyword: "pb0x" (Slater*0.75+HF*0.25) iexch=6 "pb0x" PBE0 (PBE exchange*0.75) igcx =8 don't they have to be different? Best, Sam ——— Sam Azadi Imperial College London