I calculate phonon bandstructure which have alot of imaginary frequency. However I increase the supercell many times but does not work. ?

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Phonon calculations using Vasp?

I hope all is well. we got no imaginary frequency for a compound having and if we change Kpath still the compound will be no imaginary frequency for other kpath

01 February 2024 3,385 4 View

What should be the minimum time difference between two points of data collection?

Moreover, Can anybody tell which variable(dependent, independent, mediator, and moderator) should be measured at what time?

16 November 2023 5,588 0 View

How I reduce imaginary frequency in phonon bandstructure using vasp for 3 2 2supercell?

How I reduce imaginary frequency in phonon bandstructure using vasp for 3 2 2supercell. What can I do next

22 September 2023 3,994 0 View

What is the procedure for conducting a Diary study??

is there any source where can I learn how I may conduct the diary study and what would be the procedure for collecting and analyzing the data related to a diary study?

19 June 2023 9,769 2 View

Can anyone provide the response curve of the spectrometer (Avantes)?

I am using Avantes spectrometer. A set of six spectrometers covering wavelength range from 220 to 960 nm. I need a response curve for the spectrometer equipped with two spectrometers 2400...

12 January 2023 5,103 0 View

Factor loading slightly less than 0.5 any reference to justify the item?

Can you please mention any reference that supports the use of an item less than 0.5 loading in AMOS?

21 April 2022 2,381 3 View

Comparing the data from two countries?

I want to compare the data of the two countries. Do I need to join the data of these countries and construct a measurement model to check validity and reliability? or can ensure the reliability...

17 November 2021 6,010 3 View

HOW to report a serial mediation ?

In my model i have i have two serial mediator. how can i report the results ? any good paper?

14 May 2021 2,691 3 View

Why does a direct effect insignificance?

In my model, I have three independent(goal setting, performance appraisal and feedback), one mediator(autonomy) and one dependent variables (commitment). When I calculate direct effect of only...

12 April 2021 3,241 3 View

Best online teaching platforms?

I am looking for the best online teaching platform (due to Covid-19). The features I need would be to 1: share audio, video lecture utilizing less data (due to problems of data costs for the...

07 April 2020 5,898 50 View

I am trying to find phonon, and when i run calculations, there is error ?

how to fix this error, from phq_readin : error # 1 DFPT with the Blochl correction is not implemented I am attaching my ph.in file.

23 July 2024 4,649 2 View

How to eliminate imaginary phonon frequency in phonon dispersion of Coved Graphene Nanoribbons?

Dear all, I want to calculate the phonon dispersion of 4CNR-1-0 (structure is in Fig. 2 (b) in this article Designing coved graphene nanoribbons with charge carrier mob... ) and then calculate...

17 June 2024 6,911 2 View

Can the debye temperature calculated using elastic sound velocity be used in Slack model to find Thermal conductivity?

I am trying to calculate lattice thermal conductivity using Slack model. In Slack model the lattice thermal conductivity is proportional to (Debye temperature)^3. Can I use the Debye temperature...

11 June 2024 1,719 1 View

How to parallelize "Phonon Dispersion" Calculation in QE v7.2?

I am trying to perform ph.x calculations on lead-halide perovskite primitive cell with `8 8 8` k points in scf calculation and `6 6 6` q -point grid. The calculation is computationally expensive...

12 May 2024 6,276 0 View

Difficulty in reproducing Phonon Surface State calculation using Wannier Tools package ?

I am attempting to reproduce phonon surface state calculations using the Wannier tools package. In the first step, I aim to obtain the phonon tight binding Hamiltonian from force constants or...

01 May 2024 3,029 2 View

What causes bandgaps in periodic media?

I am aware that periodically layered media (if structured properly) can produce bandgaps, however I have never found a great explanation for this in the phononics case. Can someone please provide...

30 April 2024 9,681 4 View

Do the bottom layers of the slab need to be fixed when we use DFPT or finite displacement methods to compute the phonon spectrum of a surface?

When using DFPT or the finite displacement (also known as the frozen phonon) method to compute surface phonon spectra, it is generally necessary to perform high-precision optimization on the slab...

22 April 2024 8,385 0 View

How to read the atomic displacement in Phonon Calculation in QE?

I have a long-standing question that I hope you can help me with. In phonon calculations within QE, we obtain vibration frequencies and eigenvectors from the matdyn.out file. I am particularly...

07 April 2024 299 3 View

Can we use Density Functional Theory (DFT) to calculate the second and third-order force constants of a slab?

If we aim to compute the surface phonon lifetime of a Cu(111) surface, the second and third-order force constants are essential (to put in Boltzmann transport equation). However, to my knowledge,...

07 April 2024 6,677 4 View

We found a Raman peak in the silver powder around 1000 cm-1. What could be the origin of this peak?

As we know, for Raman spectroscopy, a change in dielectric constant is required w.r.t. phonons, which does not apply to metals. Therefore, pure metals are Raman inactive. Also, this 1000 cm-1 peak...

02 March 2024 1,856 4 View