Why Acetone does not behave like its computational values?

Question

I am trying to simulate the excitation state of acetone. I ran TDDFT for it both in gas phase and solvated state in water (both implicit and explicit water).

The experimental data say that acetone undergoes n->π* transition, which means it has a higher wavelength in gas phase ($\mathrm{\lambda_{max}}=$~$276~\mathrm{nm}$) and a shorter wavelength in the solvated state ($\mathrm{\lambda_{max}}=265~\mathrm{nm}$). I started with gas phase and expected something a wavelength of about $276~\mathrm{nm}$ ($4.49~\mathrm{eV}$ ), but surprisingly I got $\mathrm{\lambda_{max}}=136.172~\mathrm{nm}$ ($9.326~\mathrm{eV}$)! I really cannot understand why there is such a big discrepancy!

Here is my GAMESS input file. What is wrong with this molecule ?

!   File created by the GAMESS Input Deck Generator Plugin for Avogadro
 $BASIS GBASIS=N311 NGAUSS=6 $END
 $CONTRL SCFTYP=RHF RUNTYP=ENERGY TDDFT=EXCITE  DFTTYP=B3LYP $END
 $CONTRL ICHARG=0 MULT=1 $END
 $TDDFT NSTATE=9 $END
 $STATPT OPTTOL=0.0005 NSTEP=99 METHOD=RFO UPHESS=MSP HSSEND=.T. $END
 $SYSTEM MWORDS=1000 PARALL=.TRUE. $END
 $SCF DIRSCF=.T. DIIS=.T. DAMP=.T. $END

 $DATA 
Title
C1
O     8.0     0.00000    -1.27900     0.00300
C     6.0    -0.00000    -0.05800     0.00100
C     6.0     1.29700     0.69100    -0.00000
C     6.0    -1.29800     0.69000    -0.00000
H     1.0     1.35900     1.32900    -0.90600
H     1.0     1.35900     1.33200     0.90300
H     1.0     2.15700    -0.01300     0.00100
H     1.0    -2.15700    -0.01400     0.00100
H     1.0    -1.35900     1.32900    -0.90600
H     1.0    -1.35900     1.33200     0.90300

 $END

Answer 1

It seems that the results of the calculations are more or less fine and the OP just misinterpreted the NIST data. As I said in my comment above, NIST does not claim that $\lambda_{\mathrm{max}}=276 \, \mathrm{nm}$. Clearly only a small region of wavelength is shown on the graph and in the paper^[1] referenced on the NIST page it is said (emphasis mine):

There are two diffuse ultraviolet bands; the first at 2800 Å. is very weak with its oscillator strength $f \sim 0.0004$ and the second at about 1900 Å is moderately intense with a maximum extinction coefficient $\epsilon_{\mathrm{m}} \sim 1000$. McMurry has identified the 2800 Å. band as a forbidden $\pi^* \leftarrow n$ transition involving excitation of a non-bonding $\ce{O}$ electron to an anti-bonding $\pi$ orbital between the $\ce{C}$ and $\ce{O}$ of the carbonyl group.

A high-resolution photoabsorption spectrum in the energy range 3.7-10.8 eV can be found, for instance, in this recent study^[2] and is more or less consistent with the result of the OP's calculations.

1. Noel S. Bayliss, Eion G. McRae, J. Phys. Chem., 1954, 58 (11), 1006–1011.
2. M. Nobre, A. Fernandes, F. Ferreira da Silva, R. Antunes, D. Almeida, V. Kokhan, S. V. Hoffmann, N. J. Mason, S. Eden, P. Limão-Vieira, Phys. Chem. Chem. Phys., 2008, 10, 550-560. (available at researchgate.net)

Answer 2

this is your output, right?

TRANSITION DIPOLE, A.U.  OSCILLATOR
                    HARTREE          EV         X       Y       Z     STRENGTH
   0  A         -193.0290234748    0.000
   1  A         -192.8724089055    4.262     0.0001  0.0000  0.0001    0.000
   2  A         -192.7831335626    6.691     0.4051 -0.0004 -0.0000    0.027
   3  A         -192.7317175333    8.090     0.0018 -0.0976  0.0001    0.002
   4  A         -192.7220472153    8.353    -0.4522 -0.0001  0.0000    0.042
   5  A         -192.7210047911    8.382    -0.0121 -0.0000 -0.0006    0.000
   6  A         -192.7176816741    8.472    -0.0001 -0.0013  0.0724    0.001
   7  A         -192.7167365427    8.498     0.0006 -0.0002  0.0075    0.000
   8  A         -192.6964881601    9.049     0.0029 -0.3152  0.0008    0.022
   9  A         -192.6862850361    9.326    -0.0022  1.1274 -0.0093    0.290

I am confused, why do you take the 9ths excitation and assume it is the experimentally measured one? The first excitation agrees reasonably quite well with the experimental data.

If you look at the exp spectrum eg here http://www.sciencedirect.com/science/article/pii/S0022407308000307 you can see that there is a 2nd absorption band below 200nm (6eV). This seems to be the 2nd excitation.

Did you look at the orbitals involved in the first excitation? I would assume it shows a n-pi* transition and then your are all good.

edit:

This paper contains some references (i cannot access the cited references therein)

• http://pubs.acs.org/doi/full/10.1021/jp046334i

They report the following

The n → π* electronic transition of acetone corresponds to the excitation of an electron from the nonbonding 2py orbital on the oxygen to the antibonding π* molecular orbital on the carbonyl. For an acetone molecule in its C2 or C2v geometry, the transition is symmetry-forbidden; as a consequence of vibronic coupling, in the gas phase, a weak band at ΔE = 4.4−4.5 eV is observed, with an oscillator strength of f ≈ 0.0004.

Do we see that in the TD-DFT output? Mostly, yes! The oscillator strength is smaller than the printout (bad program), but if you use e.g. ORCA you get a non-zero oscillator strength. It is still much smaller than the reported value but that is somewhat expected from TD-DFT in this case (partially CT-state!) The small oscillator strength is troublesome, but the excitation energy is ok. It could indicate a ghost state (=purely artificial state), but these are not often seen in hybrid-functional TD-DFT calculations. Likely all states are physical.

The first transition is a HOMO-LUMO transition and if you bother to look at the orbital it is a nice n-pi* transition as expected.