Chemissian can plot so-called **"Anvanced-function of electronic density**". Such a functions is an *any* linear combinations of charge/spin densities of one or several molecules.

#### Note: For example **Fukui function** is just a particular case of "Advanced function".

Consider the following problem: one needs to analyze the electronic density redistribution when the hydrogen molecule H_{2} formed from individual atoms H(1) and H(2)

This can be solved the next way:

- perform three calculations:

- quantum-chemical calculation of H_{2}molecule with the following coordinates:

*H1 0 0 0*

H2 0 0 0.74

- calculation of individual atom H(1) with the following coordinates:

*H1 0 0 0*

- calculation of individual atom H(2) with the following coordinates:

*H2 0 0 0.74* - add these three calculation into one Chemissian document
- click the menu
*Tools--> Analyze electronic density*, activate tab "Advanced" and create difference density function of the H_{2}molecule and individual H(1), H(2) atoms.

It is the following*linear combination (you may determine any other one with any number of atoms included)*: 1.00 * Rho(HH) - 1.00 * Rho(H(1)) - 1.00 *Rho(H(2)) - Now click
**Go!**button and**Chemissian will build the difference map**.

see also: