Questions tagged [phonopy]
Tag this when using the phonopy package for phonon calculations at harmonic and quasi-harmonic levels.
37
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Comparing phonon dispersions generated with phonopy to those generated with Quantum Espresso
I've generated a phonon dispersion for BCC lithium using the python api for phonopy. I specified the following q-point path
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4
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1
answer
67
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Why dipole correction does not work in VASP DFPT + phonopy calculation for a stable 2D material
Seems that DFPT method in VASP has many defects. It can't include vdw interaction. Now I found it also can't include dipole correction, which leads to a large negative frequency at $\Gamma$ point. I ...
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How can we calculate transverse and longitudinal optical phonon frequencies
Could you please help me to calculate the "transverse and longitudinal optical phonon frequencies" from phonopy+vasp output files?
These parameters will help me to calculate the high-...
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5
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1
answer
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Getting the Phonon Dispersion Using fix phonon in LAMMPS
I am using fix phonon in LAMMPS to get the phonon dispersion relation, but this requires a post-processing code that takes the generated binary file and produces ...
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3
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How to calculate the lattice parameter of a supercell using Phonopy? (For Quantum ESPRESSO)
I found in the internet a method to generate a supercell from the input file using Phonopy code. And I have a question if someone can clarify my doubts please. The method is as following:
We make an ...
- 1,957
4
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An issue of running Phonopy for graphene using Siesta [closed]
I have used Siesta in the example attached with phonopy to run phonon for graphene, and when I typed the command to create force ...
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Phonon Angular Momentum
Can anyone help me understand what is Phonon Angular Momentum? How does it affect thermal properties? Any relevant books and papers are welcome, if you have suggestions.
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195
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k-path for phonon band structure
I have observed in research papers that the k-path chosen for electronic band structure and for phonon band structure to be different. I am currently using VASPKIT in order to obtain the path for ...
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78
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How to determine the TA/LA by phonopy [closed]
I would like to ask how to use PHONOPY to define which band is LO, TO or ...
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5
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1
answer
85
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Phonon branch-resolved harmonic sampling
I would like to do a phonon band-resolved harmonic sampling, following the recipes from the paper by West and Estreicher (harmonic sampling). In fact, the method presented in the paper is already ...
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0
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Interpreting Phonon calculations for 2D materials [closed]
What is the meaning of phonon calculation in 2D materials? And is it enough to predict the stability of materials based on positive phonon only?
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can anyone please explain what is meaning of band.conf , mesh.conf and pdos.conf in phonon calculation? [closed]
Can anyone please explain, what is the physical meaning of band.conf, mesh.conf and pdos.conf in phonon calculation?
if it is possible please explain about tags used in it.
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Tools to Visualize Phonons
Software such as ChemCraft or GaussView is easy to find for vibrational calculations in gas phase, but I am finding it much more difficult to find good visualization software for phonons. I have ...
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7
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1
answer
844
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How to solve this Phonopy-related problem?
I have used the finite displacements method for phonon spectrum calculation, and when I typed the command to create force sets:
...
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7
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1
answer
493
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Which IBRION tag should be used for finite displacement method in calculating Phonons spectrum?
I am planning to use the finite displacement method for calculating phonon spectrum, and I have prepared the INCAR file below to try it on a transition metal trihalide monolayer (e.g., VI$_3$). I ...
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answer
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Lattice Thermal conductivity calculation error
I have been trying to calculate Lattice Thermal Conductivity on my system using QuantumEspresso. I used phonopy and phono3py.
I was successful to run these codes on Si system for practice. Now when I ...
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6
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0
answers
164
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What is the minimum supercell size for phonon spectrum calculation for this monolayer system? [closed]
Following the previous threads on this topic, I would like to know the minimum supercell size suitable for Phonon spectrum calculation using Phonopy (DFPT) for CrI$_3$ monolayer system given by this ...
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How can I find primitive axis for any bulk or 2D (monolayer) material [closed]
I am doing DFPT calculations using VASP+Phonopy.
To plot phonon band structure, I need a band.conf file in which we need to ...
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4
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answers
181
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How to correct units in the band.yaml file of QE, to band.yaml of VASP [closed]
I see from the phonopy web page 1 that the physical unit systems used for the calculators are different for different codes 1. On the same page, it is mentioned that "For these sets of physical ...
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2
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848
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Calculating lattice thermal conductivity using Quantum ESPRESSO and phonopy
How should I calculate lattice thermal conductivity in Quantum ESPRESSO? I have installed phonopy. My Linux distribution is Ubuntu.
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8
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1
answer
552
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Calculation of linear coefficient of thermal expansion using VASP-Phonopy for Hexagonal material
We use quasi-harmonic approximation using VASP-Phonopy. In whole calculation we only assume Free energy as function of volume but in case of HCP material which have ...
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8
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1
answer
189
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Phonon frequencies and free energy with respect to polymorphs
I have a material that can crystallize in either a cubic or tetragonal polymorph depending on the synthesis. I used DFPT in VASP and calculated the phonon band structures. I see that the cubic has all ...
- 1,060
7
votes
1
answer
142
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Can we translate vibrational frequencies at q-points to vibrational frequencies of atoms?
Lattice dynamics codes like phonopy output vibrational frequencies at q-points. Can we get data of vibrational frequencies for each of the atoms in the supercell? (...
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10
votes
2
answers
477
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Temperature effect on elastic constant using VASP
I want to incorporate the temperature effect on elastic constant (EC) of a system using VASP.
From literature, there are two ways which can be used to get the temperature effect on EC i) ab initio ...
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11
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1
answer
181
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Reliability about the predicted two-dimensional crystal structures based on DFT high-throughput calculation?
Computational 2D Materials Database (C2DB), 2D structures and layered materials, and 2D Materials Encyclopedia are three major databases for two-dimensional materials based on DFT calculation.
However,...
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How to determine LA/TA, ZA/ZO and LO/TO by PHONOPY
I would like to ask how to use PHONOPY to define which band is LO, TO or LA, TA, or ZO or ZA.
I attach a picture from https://iopscience.iop.org/article/10.1088/0953-8984/28/10/103005
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Why do we need to build a supercell to use the DFPT in Phonopy interfaced with VASP?
The following passage about the merits of density-functional perturbation theory (DFPT) is extracted from this seminal paper: Phonons and related crystal properties from density-functional ...
- 14.9k
10
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246
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Phonon density of states as a function of frequency vs energy [closed]
Lattice dynamics codes like Phonopy output density of states, $g_{(\omega)}$, as a function of frequency. Since $\int g_{(\omega)}d\omega$ is the number of states ...
- 5,125
13
votes
1
answer
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Phonon density of states in statistical thermodynamics
Phonon density of states (DoS), $g_{(\omega_i)}$, help understand the distribution of states across frequencies of vibration. $\int g_{(\omega_i)}d\omega_i =$ the number of states between $\omega_i$ ...
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19
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1
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What do negative phonon frequencies signify?
Negative frequencies "in general" mean the direction of displacement is reverse to that in positive frequencies.
Does it mean two frequencies with opposite signs but the same magnitude give ...
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Best practice(s) for q-points convergence in phonon density of states calculations
The answer can be a complete description of all the things we must be attentive to while converging q-points.
A peculiar thing that I feel contradicted about: Generally, we don't take an equal # of k-...
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8
votes
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Should all q-points in the first Brillouin zone be sampled in phonon density of states calculations?
For electronic density of states (DoS) calculations with VASP, it is recommended that VASP's internal symmetry routine is turned ...
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votes
2
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543
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"Input forces are not enough to calculate force constants" Phonopy error?
I am doing a phonon calculation for a phase using a 2x2x1 supercell (after geometry optimization of the structure). I am getting an error when computing the DOS and band structure after computing the ...
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How big should a supercell be in phonon calculations?
Is 2x2x2 enough, or is larger needed? I know that a convergence test must be carried out, but increasing supercell size enormously increases computational time, and I am using the Python program ...
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Can we do anything to reduce the number of displacements in a frozen phonon lattice dynamics study?
I realize that the more ordered the supercell is, the lower the number of displacements. Perhaps, we could say the same with respect to symmetry.
Is there anything that can be done to reduce the ...
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19
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1
answer
627
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What do phonon dispersion (or lattice dynamics) studies include?
I use the codes phonopy and phonopy-qha for phonon dispersion studies. phonopy-qha gives ...
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Are there differences in accuracy and reliability between the frozen phonon method and Density Functional Perturbation Theory?
When proposing or predicting new materials, whether in the bulk or in two dimensions, it is important to discuss the stability of the system. This is usually done through thermodynamics and(or) ...
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