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Questions tagged [td-dft]

For questions related to time-dependent density functional theory.

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33 votes
6 answers
4k views

What are the types of DFT?

Similar to: What are the types of charge analysis?, What are the types of bond orders?, and What are some recent developments in density functional theory?, I would like to ask: What are the different ...
Nike Dattani - No Free Time's user avatar
28 votes
3 answers
3k views

Given that Kohn-Sham DFT is strictly a ground-state method (at 0 K), how is it sufficient to describe materials in real-life applications?

Kohn-Sham DFT appears to be so popular even though it is strictly a ground-state method - all calculations are done at 0 K. How then, is it so popular when describing materials that have real-life ...
livars98's user avatar
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22 votes
2 answers
306 views

Validity of adiabatic approximation in TDDFT

In the time-dependent Kohn-Sham formalism the effective potential on electrons is given by $$ v_s[\rho(\mathbf{r},t)]=v(\mathbf{r},t)+v_H(\mathbf{r},t)+v_{xc}[\rho(\mathbf{r},t)] $$ where, $v(\mathbf{...
Verktaj's user avatar
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21 votes
2 answers
616 views

What methods are available for excited state calculations in solids?

In the spirit of a succint answer (3 paragraphs maximum) to create a useful resource, what are the types of excited state calculation available for solids? Please add to the list: Quasiparticle ...
ProfM's user avatar
  • 11.1k
21 votes
1 answer
277 views

What are the recent developments of TDDFT to simulate the excited properties of materials?

The time-dependent density functional theory (TDDFT) and the many-body perturbation method (GW@BSE) are considered as the two most popular and successful methods to describe the excited-stated ...
Jack's user avatar
  • 15.2k
20 votes
1 answer
189 views

What is the importance of electron interaction on dielectric response of crystals?

After obtaining the Kohn-Sham orbitals from a plane-wave-based self-consistent-field calculation, the dipole matrix elements could be calculated in order to determine electro-optical properties such ...
Anibal Bezerra's user avatar
17 votes
1 answer
263 views

How can reactivity indices be calculated in a time-dependent scheme?

Many reactivity descriptors can be obtained from ground state (or static) DFT as energy derivatives respect to the number of electrons, $N$, and the external potential, $v(\mathbf{r})$, like chemical ...
Verktaj's user avatar
  • 2,731
15 votes
2 answers
216 views

Is there an example in which TD-DFT was successful in describing photophysical or photochemical processes?

Time-dependent Density Functional Theory has been around for quite a while now, seeing Density-Functional Theory for Time-Dependent Systems, and so it has been developed extensively, implemented in ...
epalos's user avatar
  • 4,879
14 votes
1 answer
326 views

What are the recent developments of GW@BSE to simulate the excited properties of materials?

A twin question related to the TDDFT method is asked in another post. But any comparisons between both methods in recent developments are welcome. The time-dependent density functional theory (TDDFT) ...
Jack's user avatar
  • 15.2k
14 votes
1 answer
300 views

Is there a software that has implemented forces of TDDFT calculations for solids?

I'd like to investigate the structural relaxations of the excited state for periodic systems. BSE and TDDFT are two promising methods for this purpose. While there is a discussion on forces with BSE ...
Xiaoming Wang's user avatar
12 votes
1 answer
1k views

How do you calculate the change in dipole moment from ground to first excited state using ORCA?

How do you calculate the change in dipole moment from the ground to first excited state using ORCA? I have done DFT to get the dipole moment at the ground state and TDDFT of this neutral molecule. How ...
Bri's user avatar
  • 341
11 votes
1 answer
123 views

Regarding oscillatory strength theoretical units to experimental ones

The output of Gaussian rotatory and oscillatory strength intensities, plus a gaussian/lorentzian fit, translates to a theoretical CD/UV-vis spectra. In order to try and compare with experimental ...
C. Alexander's user avatar
11 votes
1 answer
210 views

Deviation caused by using DFT in Non-Adiabatic Molecular Dynamics

To calculate the excited state properties and processes of semiconductors (e.g. during the photocatalysis process), can be important. Non-Adiabatic Molecular Dynamics (NAMD) is one of the popular ...
Jack's user avatar
  • 2,067
11 votes
0 answers
337 views

I ran TDDFT on some small molecules. For some files, the ORCA output files cut short and contain no absorption data. What could be the reason? [closed]

Below is just the end of the output file, and the top of the input file. This is for the molecule FDICTF. The calculation did not run out of time. I ran a batch of 15 molecules, all with same ...
Bri's user avatar
  • 341
10 votes
2 answers
263 views

Is there an example where TD-DFT fails to provide sufficient accuracy for a small system, where RI-CC2 is sufficient?

Time-dependent density functional theory (TD-DFT) is considered to be more efficient (in terms of its accuracy/speed ratio) than alternatives such as the approximate coupled-cluster singles and ...
TheSimpliFire's user avatar
10 votes
1 answer
813 views

Understanding emission spectra using TDDFT calculation

I did a TDDFT calculation to get the emission spectra of my molecule. Here are the first five roots for the emission calculation: ...
Bikash Patra's user avatar
10 votes
1 answer
196 views

Is there a software that has implemented forces of BSE calculations for solids?

I'd like to investigate the structural relaxations of the excited state for periodic systems. It seems BSE is a practical method that has already been implemented in many codes for static calculations....
Xiaoming Wang's user avatar
10 votes
1 answer
440 views

Understanding absorption spectra using TDDFT calculation in NWCHEM

I did a TDDFT calculation using B3LYP functional and ground state optimized structure in NWCHEM. The TDDFT portion of the output is the following: ...
Bikash Patra's user avatar
10 votes
1 answer
110 views

Reading complex potential into CP2K

Is it possible to read a complex potential into CP2K? I have generated a potential using FDTD at a given frequency, which results in a complex result. The potential is to be read in to a real time ...
Jason M Gray's user avatar
9 votes
2 answers
2k views

Different types of transition dipole moment in ORCA output

In the ORCA output for a TD-DFT calculation, there are two types of spectra printed. One is called "transition electric dipole moment" and "transition velocty dipole moment". ...
S R Maiti's user avatar
  • 7,141
9 votes
2 answers
765 views

Is it reasonable to calculate TDDFT excitation energies at a geometry optimized with a different method?

I am working on a project where I have to calculate the TDDFT excitation energies of organic molecules (to compare to the experimental UV/visible i.e. optical absorption spectrum). Now, if I ...
S R Maiti's user avatar
  • 7,141
9 votes
2 answers
237 views

Any software that could do surface hopping?

I am trying to understand how to do the time-dependent simulation of the electron transfer, I find that the popular method is surface hopping, but I am not sure if there is any software that could ...
Jack's user avatar
  • 2,067
9 votes
1 answer
828 views

Is it possible to do TD-DFT/6-31G+(d,p) calculations on a laptop?

In the recent publication: "Density Functional Theory Calculation on the Structural, Electronic, and Optical Properties of Fluorene-Based Azo Compounds", the author claimed to have used ...
Protima Rani Paul's user avatar
9 votes
2 answers
487 views

Is there an anisotropy factor (g factor) for TDDFT absorption and circular dichroism calculations?

Experimentally, anisotropy factor is calculated by dividing the CD (circular dichroism) spectra by the absorbance spectra and multiplying by a factor of 32980 (in order to get a dimensionless quantity)...
C. Alexander's user avatar
9 votes
1 answer
266 views

Quantum Chemistry software that can calculate nonadiabatic coupling vectors between excited states using DFT/TDDFT

I am looking for software that can calculate the first-order non-adiabatic coupling vector $$\vec \tau_{ij}=\langle \varphi_i|\nabla_R\varphi_j\rangle$$ between excited electronic singlet states using ...
Hans Wurst's user avatar
8 votes
1 answer
625 views

How to extract transition density cube from .fch file in Gaussian?

I have been trying to extract the transition density cube of a simple molecule, $\ce{H_2O}$. I did a regular geometry optimization and then TD-DFT calculation with a keyword ...
aerospace's user avatar
  • 193
8 votes
0 answers
146 views

What could be the possible causes of the energy difference in the following calculation using Octopus (TDDFT) code? [closed]

I am trying to do a simple ground state energy calculation of methane molecule using the Octopus (TDDFT) code. The example is already available in the octopus manual. ...
Niraja moharana's user avatar
7 votes
1 answer
390 views

How to assign UV-vis maximum absorption wavelength theoretically by using td-DFT?

I'm currently working on the simulation of Uv-vis absorption spectra of some organic compounds, while performing TD-Dft the log file that we got contains the values of deltaE of the transition,...
diamond999's user avatar
6 votes
1 answer
112 views

Accurate electron-hole localization for charge-transfer transitions

I'm studying the nature of electronic excitation in conjugated organic dyes. To define the donor and acceptor part I've run TDDFT and CIS calculation, they both gave similar set of configurations for ...
Roman's user avatar
  • 2,373
5 votes
2 answers
1k views

Vertical transition, 0-0 transition, and experimental spectra

I am currently working on a machine learning with spectroscopy. I had learnt about the Franck-Condon principle and the vibronic coupling in photochemistry courses in my undergraduate lectures. However,...
S R Maiti's user avatar
  • 7,141
5 votes
2 answers
194 views

Trying to get concurrent results for a TDDFT calculation in Gaussian and ORCA

I am trying to do a simple TDDFT calculation in both Gaussian and ORCA from the exact same reference Geometry. I am using the same functional (making sure to use ...
Uranium238's user avatar
5 votes
1 answer
378 views

S1-T1 energy difference in Gaussian

I would like to calculate the energy difference between the first excited singlet and the first excited triplet of a given molecule in solvent, on Gaussian. In this publication, they state that using ...
Laura's user avatar
  • 1,287
5 votes
1 answer
414 views

how can I distiguish between pi-pi* or n-pi* while doing a TDDFT calculus on gaussian?

Hi I have a system that belongs to the C1 point group which is polycyclic and contains heteroatomes ,when calculating the excited states by TDDFT and after visualising the MOs that are envolved on ...
diamond999's user avatar
5 votes
1 answer
240 views

Does it make any sense to run a TD-DFT calculation with Finite-Temperature SCF active?

I recently received the task to investigate what is happening in a fluorescent molecule in different temperatures. How the electronic population is changing and how is this affecting the electronic ...
HCSthe2nd's user avatar
  • 327
5 votes
1 answer
478 views

Can a spin-flip TD-DFT singlet ground state wavefunction be written as a sum over MOs with occupancy information?

Using collinear spin-flip(SF) TD-DFT with the Tamm-Dancoff approximation, BHanHLYP and a simple test molecule (ethene, with a singlet ground state). It's my understanding, using ethene as an example, ...
srk's user avatar
  • 401
5 votes
0 answers
263 views

How to calculate singlet-triplet splitting energy with TD-DFT in ORCA?

I wish to reproduce the results from this paper by Truhlar and co-workers, where they treat a spin-forbidden reaction by considering two effective states coupled by a semi-empirical spin-orbit ...
S R Maiti's user avatar
  • 7,141
5 votes
0 answers
77 views

simulate dynamic response to laser impulse with TDDFT in SIESTA [closed]

I am trying to simulate the dynamic response of semiconductors to laser impulse, but I am not sure how to do it with TDDFT in siesta, I checked the siesta-doc, and it seems I need to construct an ...
Jack's user avatar
  • 2,067
4 votes
1 answer
58 views

Do oscillator strengths matter when matching theoretical and experimental outcomes?

I use ORCA to do TD-DFT studies. The experimental maximum absorption is esteemed to 445.0nm . Benchmark computations were conducted and this is the exemplatory (part of) the output: ...
farmaceut's user avatar
  • 677
4 votes
1 answer
58 views

Assessing excited state lifetime with TD-DFT

My question is brief — is it possible to estimate excited state lifetimes using computational chemistry (DFT/TD-DFT) tools? I am aware this may be a rough approximation (e.g., neglecting non-radiative ...
farmaceut's user avatar
  • 677
4 votes
1 answer
111 views

How do I do a PES (potential energy surface) scan for the excited electronic state?

I know how to do a PES scan for a ground electronic state. But for the nth-excited state, is it the same (i.e. an excited state optimization and just rotating the dihedral to simulate the ...
WALOWLA's user avatar
  • 91
4 votes
1 answer
480 views

Methologies to calculate excited states in Gaussian

Referring to previous questions asked here, I would like to pose a more general question about the calculation of ΔE(S1-T1) for organic molecules with the software Gaussian16. In particular, I have ...
Laura's user avatar
  • 1,287
4 votes
1 answer
155 views

How to plot absorbance from a Quantum ESPRESSO optical calculation using ε1, ε2, and energy data?

I have a calculation via DFT-RPA, which calculates epsilon_2 and energy (eV). For optical property calculation, we usually plot epsilon_2 vs energy (eV). However, I need to know to convert the y-axis ...
Sak's user avatar
  • 991
4 votes
0 answers
133 views

Absorption spectra with Gaussian [closed]

I want to calculate the absorption spectra of molecules (and possibly ions) with TD-DFT. I have used Gaussian in the past and, to my knowledge, the application of TD-DFT is implemented in this code. ...
Laura's user avatar
  • 1,287
3 votes
1 answer
72 views

optical properties in IR region

I have done geometry optimization using hybrid functional. this gives a band gap that is comparable to the experimental one. but I am also expecting my optical properties to be in IR region, but they ...
Noor's user avatar
  • 55
3 votes
1 answer
798 views

A different way to optimize triplets?

I am studying a system with TD-DFT method implemented in Gaussian. I am not sure whether this two inputs are adequate by the mean of output - optimization of T1? ...
farmaceut's user avatar
  • 677
3 votes
1 answer
171 views

Difference in energy between first excited singlet and first excited triplet with DFT in Gaussian

I want to ask a further question related to this one. I have performed the calculations as explained and obtained a difference in energy of 0.71eV with the TDA-DFT level of theory. Then, I tried to do ...
Laura's user avatar
  • 1,287
3 votes
1 answer
183 views

Is a D-Wave quantum computer able to do TD-DFT calculations?

I was reading this paper (Computing molecular excited states on a D‑Wave quantum annealer) and wondering if I can make a QUBO model for the equations used in the TD-DFT energy calculation for the ...
Hadeel Moustafa's user avatar
3 votes
1 answer
115 views

Cannot reproduce excitation energies in Orca

I do TD-DFT studies in Orca 5.0.3 on porphyrin system and hence at the very beginning I need to pick functional that reproduce excitation energies. The experimental reported values equal: 691, 656, ...
farmaceut's user avatar
3 votes
1 answer
110 views

How may I verify that my A matrix for TDA (Tamm-Dancoff Approximation of TD-DFT) from PySCF is correct?

This is a follow-up to a series of questions that I have asked here: Is a D-Wave quantum computer able to do TD-DFT calculations? (answer was "yes, but it might not be efficient") Inquiry ...
Hadeel Moustafa's user avatar
3 votes
0 answers
22 views

DFT simulations of UV-VIS spectroscopy for Semiconducting Heterojunctions

I have a course project that involves DFT. Does anyone know of any tutorials or resources to simulate UV-Vis spectroscopy of semiconducting heterojunctions using ORCA, Quantum Espresso, or any other ...
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