So, what's DFT anyway? It's a smart idea to reduce the complexity of quantum mechanics. Quantum mechanics can be super complex, even for a single atom. DFT can let you do quantum mechanics for hundreds, or even thousands of atoms. DFT is so smart it got a Nobel prize. 1/n

What's meant by "do quantum mechanics"? I mean learn the properties of something. Formally speaking, it means solving the Schrodinger equation, one of the toughest equations in physics
2/n

and when you solve the Schrodinger equation, you learn the properties of your atom via the properties of its electrons. When there are so many electrons in the atom, it becomes pretty hard to solve its Schrodinger equation 3/n

And that's where the coolness of DFT emerges: just don't bother about the electrons individually. Instead, deal with electrons as a "sea of charges". This reduced the complexity of quantum mechanics tremendously but at the expense of accuracy 4/n

And here's why different papers would get different results for the same material using DFT: DFT is an approximation, and there are many flavors of DFT, each claiming to be a better approximation. So either the two papers used different flavors, or one/both papers suck(s). 5/n

New DFT student wonders: which flavor to start with? Crystal systems? PBE is a good starting point, and then u can add sub-flavors to it. Molecules? There's a war going on now on this - if I suggest #B3LYP (traditional choice) I'll hear shots being fired but its not bad. 6/n