How to perform TD DFT calculation in Gaussian

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Performing a Time-Dependent Density Functional Theory (TD-DFT) calculation involves predicting the excited electronic states of a molecular system using DFT principles.
Remember, while TD-DFT is a powerful method for predicting electronic excitations, the choice of functional and basis set can significantly affect the results. It's crucial to choose appropriate settings for your specific system and property of interest.
#P functional/basis set TD(Nstates=N)
The DFT functional and basis set of your choice (e.g., B3LYP/6-31G(d)), and N with the number of excited states you want to compute

[@SAJALPHYS]

Very helpful video ❤

[@naserianikambaine4934]

Thank you very much.

[@success7669]

is these set up the same for radical? I mean TDDFT? and how we could setup SRSH?

[@quantumguruji]

same for radicles

[@AbhishekPMT]

how to calculate the molar Gibbs free energy of a single gas molecule in Gaussian??

[@quantumguruji]

Follow this video to calculate Gibbs free energy (kzbin.info/www/bejne/goLHan6Dm8yhhrc&ab_channel=QuantumGuruJi) Convert Gibbs Free Energy to Molar Gibbs Free Energy Convert from Hartree to kJ/mol: The Gibbs Free Energy from Gaussian is in Hartree per molecule. To convert it to kJ/mol, use the following conversion factors: 1 Hartree = 2625.5 kJ/mol Avogadro's number (N_A) = 6.022 ×10^23 molecules/mol Calculate the molar Gibbs Free Energy as follows: Molar Gibbs Free Energy (kJ/mol)=Gibbs Free Energy (Hartree) × 2625.5 For example, if the Gibbs Free Energy is -76.421032 Hartree: Molar Gibbs Free Energy (kJ/mol) = − 76.421032 × 2625.5 ≈ −200585.56 kJ/mol

[@AbhishekPMT]

@@quantumguruji But it is too high, when we calculate the the Gibbs free energy of methane through same method, it molar gibbs free energy is -106718.85 kJ/mol but in NIST database the gibbs free energy is around 130 kJ/mol?

[@dios_1111]

How to generate energy optimization plot in guass using dft?

[@quantumguruji]

Open your output file with gauss view ...right click on molecule ...Results -> Optimization Plot You will see all the steps with energy plot.

[@dios_1111]

@@quantumguruji but the optimization plot tool is not enabled. It's not working

[@quantumguruji]

@@dios_1111 I guess, you might not have done the geometry optimization. Simply single point calculations will not enable this option. Or other reason may be convergence failure or unfinished calculation.

[@dios_1111]

@@quantumguruji I am calculating it from optimized file also when I am checking in summary, it is showing that it is converged. Still it's not working I am not able to find where the glitch is. What does unfinished calculations mean?

[@quantumguruji]

@@dios_1111 if you are performing geometry optimization, you should see the optimization plot...if you it's not enabled..means you are doing some mistakes..see carefully