I want to perform the absorption and emission of a molecule to get the corresponding energies but i am facing a problem in making the PCM corrections. I followed the example, two of its step are given below. Can anybody help to give the input..
second step: Vertical excitation with linear response solvation. This is a TD-DFT calculation of the vertical excitation, therefore at the ground state equilibrium geometry, with the default solvation: linear response, non-equilibrium. We perform a single-point TD-DFT calculation, which defaults to non-equilibrium solvation. The results of this job will be used to identify which state or states are of interest and their ordering. These results give a reasonable description of the solvation of the excited state, but not quite as good as that from a state-specific solvation calculation. In this case, we see that the n→π* state is the first excited state. Next, we will use the state-specific method to produce a better description of the vertical excitation step.
%oldchk=01-ac
%chk=02-ac
# B3LYP/6-31+G(d,p) TD=NStates=6 SCRF=(Solvent=Ethanol)
Geom=Check Guess=Read
Acetaldehyde: linear response vertical excited states
0 1
The vertical excitation (absorption) to first excited state from the non-equilibrium solvation linear response calculation:
Excited State 1: Singlet-A" 4.3767 eV 283.28 nm f=0.0000 =0.000
Thus, the ground state to first excited state absorption is at 283.28 nm, computed via the linear-response approach.
Step 3: State-specific solvation of the vertical excitation. This will require two job steps: first the ground state calculation is done, specifying NonEq=write in the PCM input section, in order to store the information about non-equilibrium solvation based on the ground state. Second, the actual state-specific calculation is done, reading in the necessary information for non-equilibrium solvation using NonEq=read, and specifying the checkpoint file from Step 1:
%oldchk=01-ac
%chk=03-ac
# B3LYP/6-31+G(d,p) SCRF=(Solvent=Ethanol,Read)
Geom=Check Guess=Read
Acetaldehyde: prepare for state-specific non-eq solvation
by saving the solvent reaction field from the ground state
0 1
NonEq=write
--link1--
%chk=03-ac
# B3LYP/6-31+G(d,p) TD(NStates=6,Root=1)
SCRF=(Solvent=Ethanol,ExternalIteration,Read)
Geom=Check Guess=Read
Acetaldehyde: read non-eq solvation from ground state and
compute energy of the first excited with the state-specific method
0 1
NonEq=read
Here is the energy of first excited state—at the ground state optimized geometry—from the non-equilibrium solvation state-specific calculation:
After PCM corrections, the energy is -153.687679826 a.u.
Subtracting this energy from the ground state energy (from step 1) gives the ground state to first excited state absorption including the state-specific solvation correction: at 277.69 nm
please see the link to understand it better
http://www.gaussian.com/g_tech/g_ur/k_scrf.htm
Dear Haamid,
What is the problem you are facing? Implicit solvation is already included in the example through the SCRF keyword... Could you be more precise? The gaussian link you posted is self-explanatory.
Dear Hamid,
Your question is not clear to me. Can you be more specific? NonEq=Read will give you vertical absorption value in State Specific approach.
If I understood correctly
In the link, after step 3 and 6; it said that "After PCM corrections, the energy is -153.687679826 a.u. " and so on.
The question is how to do the correction by myself?
can anyone offer any explanation or simplification?
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