I am studying statistical mechanics and force-fields, and I see a lot of this formula being thrown around with no explanation: $$U_{\mathrm{dihedral}} = \begin{cases} k(1+\cos (n\psi + \phi)),& n>0 \\ k(\psi - \phi)^2, & n=0 \\ \end{cases} $$ The only explanation I read is: this...

If all the excited molecules at higher S1 vibrational states rapidly relax to the lowest S1 vibrational state, why do the fluorescence transitions from v' = 1, v' = 2, v' = 3, and other states to v" = 0 have different wavelengths? Why don't they all relax to v' = 0 first and then all transition t...

Is there any Pythonic way (a.k.a: a module, an rdkit package, etc) or an API I can use for ADME predictions? I need to prioritize some compounds for purchase/synthesis and some sort of ADME scoring might help me rule out most of them. I am aware of tools like SwissADME but given the amount of com...

I am quite a beginner in DFT and I am studying the theory behind the computational tools. I have some doubts about the Columb approximate functional term: $U[n] = \frac{1}{2} \int d^3 r \int d^3 r^\prime \frac {n(\mathbf{r}) n(\mathbf{r}^\prime)}{|\mathbf{r} -\mathbf{r}^\prime|}$ If I use the de...