[Pw_forum] magnetic field
Hi
I am a PhD student and i have begun quantum-espresso soft ,recently.
I saw this formula in Input data description for constrained_magnetization:
LAMBDA * SUM_{i} ( magnetization(i) - fixed_magnetization(i))**2
I don’t understand how to be used this formula in quantumespresso.
For example I took 0.2 Ry for magnetic field in my output. but I don’t know how
to transfer Ry toTesla?
I used this formula: U = μ. B (formula 1)
Is this correct?
Actually Iknow Total magnetization without applying magnetic field is 2.67
magneton bohrafor Fe and I know Fe can have Total magnetization =4 , totally.
Then i want to achieveTotal magnetization = 4 when I applyMagnetic field.
So for this work idid 4 – 2.67= 1.33 magneton bohra and I put
fixed_magnetization(3) = 1.33magneton bohra and I took -0.03 Ry for magnetic
field in my output.
I transfered 0.03 Ryto joule and I achieved 0.6 10^-19 joule and I transfer
1.33 magnetonbohra to joule/Tesla and I achieved 12.3 10^-24 joule/Tesla.
Then I used thisformula: U = μ . B and I achievedB = 5000 Tesla , approximately
and Ithink this amount is unreasonable.
And if I use thisformula: u= B^2/2 μ . (formula2)
I wont havepermibility for different kinds of nano particles for example Fe3o4
that I amworking on it.
And my last questionis: i did my calculation Collinear, is this correct? Or I
should do my calculationnoncollinear?
Please guide me.My phone number:00989125535899
My email: mems_agh...@yahoo.com
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Re: [Pw_forum] transverse acoustic, longitudinal acoustic, and out-of-plane transverse acoustic
> 1- Does the dimension of Supercell for phonon calculation determine > by nq1, nq2,and nq3 in the phonon input file? The parameters nq1, nq2,and nq3 is determine the Monkhorst-Pack grid for the DFPT calculation (phonon calculation) that done in q-space (you calculate the dynamical matrices explicitly and not the force constants). In DFPT there is no supercell but the convergence with respect to q-points is similar to the convergence with respect to the size of the supercell in supercell approaches. > 2- we know that the lowest three dispersion in the phonon spectra > show the three acoustic branches, but how can I find which one is > for TA, LA, and ZA? Phonons do not have just transverse or longitudinal polarization. There are phonons with polarization that is neither transverse nor longitudinal (although transverse and longitudinal polarizations are off-course possible). The most general polarization is elliptical. In general, the polarization vector is complex and you can know it from the calculation (after diagonalization of the dynamical matrices). You have this information in the dynamical matrices files which is output of the phonon calculation and also you have it in the output of matdyn.x in the file matdyn.modes. We recently publish a work in which we analyze the polarization of a complex acoustic phonon in the corner of a hexagonal Brillouin zone: http://journals.aps.org/prb/abstract/10.1103/PhysRevB.94.174305 You can maybe find it interesting. Uri Argaman Ben-Gurion University Israel ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
[Pw_forum] transverse acoustic, longitudinal acoustic, and out-of-plane transverse acoustic
Dear QE Users I 'm going to calculate the Phonon dispersion with Quantum ESPRESSO (version 6.0). The acoustic spectra consist of three branches which are transverse acoustic (TA), longitudinal acoustic (LA), and out-of-plane transverse acoustic (ZA).I have two questions: 1- Does the dimension of Supercell for phonon calculation determine by nq1, nq2,and nq3 in the phonon input file?2- we know that the lowest three dispersion in the phonon spectra show the three acoustic branches, but how can I find which one is for TA, LA, and ZA? thanks for your reply.Best RegardsAli___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
