To do a density difference plot you need=20 to obtain the excited state density (which is not computed by default=20 because it requires additional computational cost over just the excited=20 state energy), for example:

You first run a typica= l TDDFT job:

%mem=3D2500MW
%NP= rocshared=3D8
%chk=3Dtest-ex1-density.chk
# B3LYP/6-31g TD(NStates=3D= 10)

Title: HCOOH molecule - inital= excited state calculation

0 1

--= -------------------------

Than you run a second job to extrac= t the density from your root of interest using the .chk file from above:

%mem=3D2500MW
%NProcshared= =3D8
%chk=3Dtest-ex1-density.chk
# B3LYP/6-31g TD(read,root=3D1) dens= ity=3Dcurrent
geom=3Dcheck guess=3Dread

Title: HCOOH molecule (= Read energy results from previous

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 TD job and add the computation of=

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 the dens= ity for excited state 1)

0 1

When the job is done, you may open the checkpoint file with GaussView and,=20 > from the "Surfaces/Contours" option in the "Results" me= nu, you can=20 generate a cube of the SCF (ground state) density and another cube of=20 the CI (excited state) density (in this example "Root=3D1" select= s that it is excited state 1 the one for which the density was computed). Once=20 you have these two cubes, you can generate there also a third cube that=20 is the subtraction of the two other cubes, thus the density difference.=20

=A0or-

Using cubegen you may generate the= ground state and excited state cubes and subtract them:

cubegen 0 density=3Dscf scf.cu= be 0 h

cubegen 0 density=3DCI root1.cube 0 h

Than you sub= tract the two:

$ cubman
Action [Add, Copy, Difference, Properties, SUbtract, SCale, SQuare]? su<=
/b>
First input? root1.cube
Is it formatted [no,yes,old]?  y
Opened special file b.cube.
Second input? scf.cube
Is it formatted [no,yes,old]?  y
Opened special file a.cube.
Output file? difference_density.cube =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=
=A0=A0
Should it be formatted [no,yes,old]?  y
Opened special file c.cube.

That should do it, let me k= now if you have any questions.

Jessica

On Tue, Apr 30, 2013= at 11:16 AM, Radoslaw Kaminski rkaminski.rk a gmail.com <owner-chemistry,+,ccl.net> wrote:

Sent to CCL by: "Radoslaw =A0Kaminski" [rkaminski.rk{:}gmail.com]
Dear All,

We would like to compute the difference density between the ground state an= d the excited state of the molecule. The ground state is singlet, and it wa= s computed in Gaussian09 using the following commands:

# B3LYP/6-31G** Int=3DUltraFine

Then we did the excited state computations on exactly the same geometry wit= h

# B3LYP/6-31G** TD=3D(NStates=3D20,50-50) Int=3DUltraFine

and found that the excited state of interest is the one designated number 2= . This, our following computation was:

# B3LYP/6-31G** TD=3D(NStates=3D20,50-50,Root=3D2) Int=3DUltraFine

In the first and the last cases the CHK files were printed and using the ut= ility formchk were transformed into the FCHF files. The following ones were= used for the computation of electron density grids with the cubegen utilit= y. However, in both cases we got exactly the same electron density grid (i.= e. their difference is zero). We tried some options in the cubegen utility,= but with no result. The Density=3DCurrent is not available in cubegen.

How should be approach this problem? The main point is to extract the elect= ron density grids for ground and excited singlet states (with the same geom= etry or course). Examples of input files would be of a great help.

Thanks in advance,

Radek

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