Re: [QE-users] IR calculation for oriented single crystal
Hi Zac, You might look at a Python package called PDielec on GitHub ( https://github.com/JohnKendrick/PDielec ). It has the capability of calculating the IR spectrum (reflectance, absorption and transmission) for single crystals either as thick slabs or thin films. For powders it uses an effective medium theory approach to calculating the frequency dependent permittivity, from which the spectrum can be determined. It can also be used to view the phonon mode molecular and atomistic motion and provides some basic break-down of the energy in each mode in terms of internal and external modes. It has an interface to several packages, including Quantum Espresso, VASP, CRYSTAL, AbInit and CASTEP. John Subject: [QE-users] IR calculation for oriented single crystal From: Zack Gainsforth Date: 18/03/2022, 05:23 To: Quantum ESPRESSO users Forum Hi All, I have set up a calculation using pw.x -> ph.x -> dynmat.x successfully and plotted myself an IR spectrum. The match to the experimental spectrum is good. However, this is an IR spectrum assuming a powder where the photons are exciting all the modes. I’d now like to calculate the spectrum for a single crystal and specify the electric vector of the photon relative to the crystal. It should preferentially excite certain modes. Is there a straightforward way to do this using ph.x + dynmat.x? Or perhaps a way to read/print the dipole vectors for each mode so I can dot it with my photon’s e-field? Or another way of thinking about this which is more efficient? (Maybe I missed something in the documentation!) Thanks, Zack ___ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples ___ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
Re: [QE-users] IR calculation for oriented single crystal
Hello Zack, the code that computes the IR cross sections is in subroutine RamanIR at line 150 of file LR_Modules/dynmatsub.f90. If you ignore the Raman parts, it is literally 10 lines: do nu = 1,3*nat do ipol=1,3 polar(ipol)=0.0d0 end do do na=1,nat do ipol=1,3 do jpol=1,3 polar(ipol) = polar(ipol) + & zstar(ipol,jpol,na)*z((na-1)*3+jpol,nu) end do end do end do infrared(nu) = 2.d0*(polar(1)**2+polar(2)**2+polar(3)**2)*irfac ... some raman stuff ... endo do It should be straightforward to adapt it to whatever you need. Keeping in mind that "zstar" is the effective charge matrix of atom "na" and z(3nat, 3nat) is the matrix of phonon polarizations. Otherwise, you can have z printed by dynmat by setting the variable fileig = 'file_name.txt' and then do the calculation in some other way. hth Dr. Lorenzo Paulatto IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université phone: +33 (0)1 442 79822 / skype: paulatz http://www.impmc.upmc.fr/~paulatto/ - https://anharmonic.github.io/ 23-24/423 B115, 4 place Jussieu 75252 Paris CX 05 On Mar 18 2022, at 6:23 am, Zack Gainsforth wrote: > Hi All, > > I have set up a calculation using pw.x -> ph.x -> dynmat.x successfully and > plotted myself an IR spectrum. The match to the experimental spectrum is > good. However, this is an IR spectrum assuming a powder where the photons are > exciting all the modes. I’d now like to calculate the spectrum for a single > crystal and specify the electric vector of the photon relative to the > crystal. It should preferentially excite certain modes. > Is there a straightforward way to do this using ph.x + dynmat.x? Or perhaps a > way to read/print the dipole vectors for each mode so I can dot it with my > photon’s e-field? Or another way of thinking about this which is more > efficient? (Maybe I missed something in the documentation!) > Thanks, > Zack > ___ > The Quantum ESPRESSO community stands by the Ukrainian > people and expresses its concerns about the devastating > effects that the Russian military offensive has on their > country and on the free and peaceful scientific, cultural, > and economic cooperation amongst peoples > ___ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu) > users mailing list users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users > ___ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples ___ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
[QE-users] IR calculation for oriented single crystal
Hi All, I have set up a calculation using pw.x -> ph.x -> dynmat.x successfully and plotted myself an IR spectrum. The match to the experimental spectrum is good. However, this is an IR spectrum assuming a powder where the photons are exciting all the modes. I’d now like to calculate the spectrum for a single crystal and specify the electric vector of the photon relative to the crystal. It should preferentially excite certain modes. Is there a straightforward way to do this using ph.x + dynmat.x? Or perhaps a way to read/print the dipole vectors for each mode so I can dot it with my photon’s e-field? Or another way of thinking about this which is more efficient? (Maybe I missed something in the documentation!) Thanks, Zack ___ The Quantum ESPRESSO community stands by the Ukrainian people and expresses its concerns about the devastating effects that the Russian military offensive has on their country and on the free and peaceful scientific, cultural, and economic cooperation amongst peoples ___ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
