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**Homework Statement::**difference between DFT and TDDFT in Gaussian 09 software?

**Relevant Equations::**hello , I hope this message finds you well

Please I want to know what is the difference between DFT and time‐dependent density functional theory TD-DFT and why we use it in the measurement of electronic absorption spectra .

Thank you in advance

hello , I hope this message finds you well

Please I want to know what is the difference between DFT and time‐dependent density functional theory TD-DFT and why we use it in the measurement of electronic absorption spectra .

Thank you in advance