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Questions tagged [td-dft]

Questions related to Time-dependent density functional theory (TDDFT) is a quantum mechanical theory used in physics and chemistry to investigate the properties and dynamics of many-body systems in the presence of time-dependent potentials.

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How to calculate transition dipole moment from two known wavefunctions

I am interested in calculating the transition dipole moment (TDM) from the information from two wavefunctions of different states. This is somewhat similar to calculating the molecular dipole moment which was previously answered here: How to…
brose
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Interpretation of TD-DFT results

For the first time I'm doing TD-DFT calculations (wB97XD functional) in Gaussian 09 for an open-shell system and the results look like the hell of a mess for me. The molecule is rather big, so I started with just 10 excited states to see how it…
Wildcat
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Excited-states properties with traditional density functional theory

Recently I was shown the book "Density Functional Theory II, Relativistic and Time Dependent Extensions" by Nalewajski in which a chapter from E. K. U. Gross et al. is printed. [1] This chapter contains an interesting statement in it's…
pH13 - Yet another Philipp
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How to interpret orbital transition in TDDFT?

Consider the following TDDFT run with GAMESS: ! 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…
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Can you explain DFT and TDDFT functioning (math aside)?

I have been recently reading a lot on the quantum mechanical theory regarding Density Functional Theory, DFT, and Time Dependent Density Functional Theory, TDDFT (Oscillatory and Rotatory Strengths in particular) in order to understand how first…
C. Alexander
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Calculating singlet-triplet gap and open-shell singlet character

I am trying to calculate the singlet-triplet energy gap ($S_0-T_1$) of a conjugated system (18 atoms). For the singlet $S_0$ state, assumed to be closed shell, the Gaussian options were opt=tight b3lyp/6-311g(d,p) integral(ultrafinegrid) ... 0…
kimdazar
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Changing the level of theory for organometallic compounds

I'm finishing my Ph.D. in Inorganic Chemistry and having a debate with my supervisor. The work in question have two organometallic compounds A and B. The structures are based on X-Ray Diffraction, so I already have a good molecular frame and just…
HCSthe2nd
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Oscillator Strength and Absorption Intensity in TDDFT

When I run a linear-response time-dependent DFT calculation in my favourite electronic structure program, for each excitation I'm given an oscillator strength, $f_i$, and transition dipole moment $$\boldsymbol{\mu}_i = \int\Psi_0\hat{\mu}\Psi_i…
user213305
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Is there a relation between transition density and density differences?

When I have an excited state, is there a relation between the transition density associated with this electronic transition and the density difference between the excited state density and the ground state density? Can the transition density be…
Pablor
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High-temperature DFT

Why is it so difficult to perform DFT calculations that consider temperature? I have seen that time-dependent DFT is needed to model systems at high temperature. Why is this the case? What about finite temperature functionals? Why is it also…
Wychh
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Is there an anisotropy factor (g factor) for TDDFT Abs and CD calculations?

Experimentally, anisotropy factor is calculated by dividing the CD spectra by the absorbance spectra multiplying by a factor of 32980 (in order to get a nondimensional quantity) Theoretical calculations can be performed via TDDFT to obtain rotatory…
C. Alexander
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How to Locate the Excited State Dipole Moment in Turbomole Output (TD-DFT)

I want to calculate the dipole moment for the first excited state with a Q.C. program (TURBOMOLE: TD-DFT). The calculation lists the following output: ground state total dipole moment: -1.129096 -2.295685 0.000000 I think that's…
tmartin
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Absorption and emission at same wavelength?

Is it possible for a molecule to absorb and emit at the same wavelength? What is the reason behind it? I’m working on charged tin porphyrins and got the excitation and emission (fluorescence) wavelength around 400 nm.
Pavithra J
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How to interpret TD-DFT results for finding λmax and amplitude

I am trying to understand how to interpret the TDDFT results ( I know there is another post for this but it does not answer my question ). Here is part of the result from GAMESS: I downloaded Chemissian and this is its result for this state: I…
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Which is most reliable excitation energy: LUMO-HOMO energy or TD-DFT excitation energies?

After running a TD-DFT , we can calculate the HOMO-LUMO difference and then calculate the the excitation energy. Another approach is just simply pick the energies calculated in the TD-DFT and use them. For me the latter makes more sense as that's…
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