ChargeCalculator:FAQ

I have more NMR models, how can I upload all?

I am getting a warning about atoms types with missing parameters.

I am getting an error about unknown chemical elements.

I am not getting any charges...

I got a warning that some atoms were skipped...

Why are the charges from different sets so different, and how are these differences relevant? Explain charge definitions, QM reference data and EEM parameters...

How do I choose the best parameter set? Discussion above plus what to do with charges...

How do I add parameters if they do not exist? Explain structure of the xml file; Explain how to approximate parameters (e.g., based on electronegaitivity) Add procedure, copy/paste.

Can I combine parameter sets if I have a biomacromolecule which binds a drug like molecule? Not really necessary (the parameters for biomolecules seem good enough). Explain how to use chemical elements efficiently.

Can I get good electrostatic potentials? Some papers report such. Also, some charges better than others...

Can I get dipole moments? In general, no. The concept of atomic charges has its limitations. Dipoles and higher order multipoles are known to be poorly approximated by a point charge model. You may try though... maybe to compare the dipoles of derivatives of the same molecule...

How is EEM empirical, and how is it related to QM?

Start by having a look at the main terms used by ACC, or return to the Table of contents.