Multiwfn forum

Dear mest2309,

The way of generating density difference map between excited state and ground state in fact has been substantially illustrated in Section 4.18.3 of the manual.

The easiest way to do this is generating .wfn file for S0 and S1, respectively, and then use custom operation of main function 5 to plot the isosurface map.

First, optimize your molecule at S0 state to generate the S0 geometry, and then use below input file to generate .wfn file for S0:

# B3LYP/6-311G** out=wfn

test

0 1
[Optimized S0 geometry]

C:\S0.wfn

Then use this file to generate .wfn for S1

# B3LYP/6-311G** TD density out=wfn

test

0 1
[Optimized S0 geometry]

C:\S1.wfn

Next, boot up Multiwfn and input following commands
C:\S1.wfn // Load excited state wavefunction file
5 // Generate grid data
0 // Set custom operation
1
-,C:\S0.wfn // Property of ground state wavefunction will be substracted from that of excited state wavefunction
1 // The property to be studied is electron density
2 // Medium quality grid (if your system is large, select 3 to use high quality grid to get better result)
-1   // Visualize isosurface

Then you will see density difference isosurface map corresponding to rho(S1)-rho(S0) at S0 geometry, the map exhibits the charge redistribution during vertical excitation. You can adjust "isovalue" parameter in the GUI window to make the graph looks better.

Best regards,

Tian