I read that B3LYP is a hybrid functional which uses some HF method and some DFT method for its calculations. According to this page: my professor told me that you can set the proportions of each method that the B3LYP uses yourself, so for example you can make it so it uses 70% HF and 30% DFT or 20% HF and 80% DFT etc. I'm trying to figure out how to do that. More specifically, I want to alter the proportion of the HF and slater functionals that B3LYP uses. According to this page: www.gaussian.com/g_tech/g_ur/k_dft.htm [Broken] the route section for the B3LYP method is as follows: #P BLYP IOp(3/76=1000002000) IOp(3/77=0720008000) IOp(3/78=0810010000) I'm confused about what these 3 terms represent. If I wanted to increase the amount of HF that B3LYP uses, what would I change in that route section? In the Gaussian manual, they say that Gaussian can use any model of the form: P2EXHF + P1(P4EXSlater + P3ΔExnon-local) + P6EClocal + P5ΔECnon-local heres a screenshot of this section of the manual: Anyone know how I can alter the amount of HF used by B3LYP by altering that route section?