Hi DrDu. I'm still not clear. In DFT the PDE in non-linear. Now what is the integration you are talking about? Recasting the PDE in functional form? If so can we solve it analytically for a functional of that sort? I can understand your argument for computed say Hartree potential from the...
I'm curious to know why chemists like to use Gaussian basis set in case of an ab-initio (ex.DFT) calculation. I understand that the molecules that are of interest to chemists are non-periodic and hence plane wave basis is not useful, but can't they use other real space basis like a grid? What...
Yes I had a look at wikipedia. But its confusing. For example If I have 3 operators (2 annihilation (A) and one creation (C)). How must i proceed? Can i just use CAA or ACA? I believe both will give a zero expectation for vacuum state? Which of them must be used for the norm order in this case
I'm confused with the definition of a norm ordering of operators. The basic definition of norm ordering as understood by me was "Place the annihilation operators to right and creation operators to the left". However I also read another definition "The motivation of norm ordering is to ensure...
I also think graphite is more preferred at room temperature. Also i would like to know if DFT can predict exactly what crystal structure is preferred at what temperature and pressure. I'm also just curious what happens to the fermi distribution of electrons within an atom with change in...
Ok i think i got confused. LJ and others are emperical potentials used in MD simulations. I don't have a good idea about Bravais lattice and will get back about it once i learn more details. How about the question above? Which allotrope of C is most preferred and why?
.
Sorry but do please correct me if I'm wrong. I think the only exact potential that has been calculated till date is the Learnado Jonnes Potential. I think all the other first principle methods lag way behind in identifying the exact potential of the system. If that's the case, how do you...
Hi
Well I have been thinking of this quite sometime, but i really dint know anyone who could answer my question. We all know that may elements exist in the form of crystals e.g. Si, Cu etc. And they have very specific crystal structure like Diamond for Si and face centered for Cu. Can we...
@canoe
I don't remember exactly, but i definitely remember the precision of calculation was extraordinary. I'm trying to recollect it but not sure
@phrak
Its an amazing conception, you have put down things in a beautiful and a clear way about the vague things that i had thought, but it...
Yeah that was my basic idea, how did it come up. But I have two important questions from the replies above
@Pengwuino
Well i don't know much about general relativity, but i had thought that based upon the mass of Earth and other related values, you could calculate the gravity of Earth to...
Ok that's how i always get started off with, very dubious :). Well ok I can put it this way. I know E is proportional to frequency. Accepted. And why is the quantized part needs to be hv? Why can't I have some different value for 'h'? I think when Planck and Einstien proposed it, they had...
@ Naty1
That' s very close what i had tried to frame. Maybe a better way to ask is what causes such illusions in a camera? And by the way your answer was very abstract. Can you please explain in detail about the same
Now this might seem to be a very stupid question. But neverthless, I don't understand why the fundamental quantization of energy must be hv? why not any value lower or higher like hv^2 or h/v^2. Is it possible to prove that this value of quantization is most favourable than any other value...
Well even i have just started to use it. I also have issues. From example I don't understand what it means by space group symmetry in GULP. I'm wondering what would be its value for silicon. Also I would like to know after defining the position of systems, how should i give a periodic boundary...