Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
Dear all, I am looking to know the possibility of asr rule for non zero q point (along any other special point from GAMMA direction) Is it possible???. If no, How can PWscf phonon dispersion plots contains LO-TO splitting in whole phonon dispersion relation! Help me in this doubt... Thanks in advance with regards S. Appalakondaiah PhD Student University of Hyderabad India. ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
Dear Sir, Thank you for the suggestion. Now, I found imaginary acoustic modes (around -80 cm-1) at ambient conditions and the same closes to zero at high pressures using with out using Born effective charges ( I changed T to F and removed the charges )in .fc file. On the other side, All my frequencies are positive from ambient to entire pressures using with born effective charges. It is bit surprising me. Am I miss some thing If possible please provide me the IBZ special points of BCT structure with Pwscf basis vectors for c/a > 1 with regards S. Appalakondaiah PhD Scholar University of Hyderabad ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
>> >> Also, I want to know the details (or please refer any source or >> tutorial) and difference of *"fleig"* and *"fldyn". *Surprisingly I was >> not able to find any frequencies in fidyn out put file. My out put is as >> follows I forgot this part.. fldyn contains the dynamical matrix, the frequencies and fleig contains the eigenvectors of the dynamical matrix; flvec contains the atomic displacements, which are just flvec divided by the square root of the atomic mass. It's actually the content of flvec that you have to compare with the q-point to decide if a mode is L or T. cheers -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Université Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05 ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
LO-TO splitting is a long-range effect, as such it only occurs in the vicinity of Gamma. You can try to make a copy of the force constant file, where you remove the effective charges, i.e. you remove these lines: T 2.2192318 0.000 0.000 0.000 2.2192318 0.000 0.000 0.000 3.5742157 1 -0.5300825 0.000 0.000 0.000 -0.5300825 0.000 0.000 0.000 -2.0015990 2 -0.5300825 0.000 0.000 0.000 -0.5300825 0.000 0.000 0.000 -2.0015990 3 1.0610398 0.000 0.000 0.000 1.0610398 0.000 0.000 0.000 4.0034960 and do the dispersion with matdyn again. You can then compare the two dispersion to see where the long range LO-TO splitting kicks in. > > Also, I want to know the details (or please refer any source or > tutorial) and difference of *"fleig"* and *"fldyn". *Surprisingly I was > not able to find any frequencies in fidyn out put file. My out put is as > follows -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Université Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05 ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
Dear SIr, Sorry for not provide the symmetry of the system. My system crystallizes in Body centered tetragonal (ibrav=7); 3 atoms/cell with celldm(1)= 8.017350 and celldm(3)= 1.660948. In detail, I found huge splitting of the LO and TO modes of IR modes at ambient pressure (in the Gamma point level), where as the gap was closed under pressure. The same I want to check with complete dispersion as well as try to compute the effect on other special points in IBZ. Of course I finished the phonon dispersion calculations with LO-TO splitting but I am not able to zoom out the LO-TO (or LA-TA) in other directions Also, I want to know the details (or please refer any source or tutorial) and difference of *"fleig"* and *"fldyn". *Surprisingly I was not able to find any frequencies in fidyn out put file. My out put is as follows Dynamical Matrix in cartesian axes q = (0.01000 0.0 0.0 ) 11 0.04011368 0.0. 0.0. 0.8840 0. 0.0.03267074 0.0. 0. 0. -0.88400. 0.0.27929359 0. 12 0.01491749 0.0. 0.0. -0.00016204 0. 0.0.00747601 0.0. 0. If possible please suggest me the high symmetry points of the BCT structure for PWSCF with c/a> 1. My Basis vectors are crystal axes: (cart. coord. in units of alat) a(1) = ( 0.50 -0.50 0.830474 ) a(2) = ( 0.50 0.50 0.830474 ) a(3) = ( -0.50 -0.50 0.830474 ) Thanks in advance with regards S. Appalakondaiah PhD student University of Hyderabad ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
You can define a band as being LO or TO by continuity, but it won't necessarily be Longitudinal or Transverse i nthe entire Brillouin zone. In particular, from the [1/2 1/2 1/2] point I cannot say anything. Especially since I do not know our cell geometry. kind regards On 20/11/14 17:43, Kondaiah Samudrala wrote: > Dear Sir, > Sorry for the eps figure. Now I attached new figure with pdf > extension In the mean time, I am following the same definition for > LO-TO splitting at Gamma point level. But, I am not clear about the > below sentence far from Gamma. > > > "An the end of the dynamical matrix file you have the frequencies and > the atom displacements (3 times number of atoms complex numbers). If the > displacement for every atom is parallel to the q-point, the mode is > Longitudinal; if it is orthogonal, the mode is Transverse. In every > other case it is neither. You can then associated the frequency with the > label.". > > I would like to know that is there any possibility to know more details > far from Gamma point. Here with I am adding the ip and ops of matdyn.x ( > Here I am using only one special point in the IBZ) > > *Matdyn.in :* > &input > asr='crystal',q_in_band_form=.true. > fleig='matdyn.eig', fldyn='AB22.dyn',flfrc='AB2444_with_ASR.fc', > flfrq='AB2_with_ASR.freq' > / > 1 > 0.5 0.5 0.5 2 > > *AB2.dyn* : > Dynamical Matrix in cartesian axes > > q = (0.5 0.5 0.5 ) > > 11 >0.03952920 0. -0.00374183 0.0. > 0. > -0.00374183 0.0.03952920 0.0. > 0. >0. 0.0. 0.0.29542189 > 0. > 12 >0.02007831 -0.0009 -0.01131717 0.006725040. > 0. > -0.01131717 0.006725040.02007831 -0.00090. > 0. >0. 0.0. 0. -0.03673002 > 0.00282937 > 13 > -0.04191744 0.00060.00162178 -0.000699500. > 0. >0.00162178 -0.00069950 -0.04191744 0.00060. > 0. >0. 0.0. 0. -0.25545367 > -0.00387305 > 21 >0.02007831 0.0009 -0.01131717 -0.006725040. > 0. > -0.01131717 -0.006725040.02007831 0.00090. > 0. >0. 0.0. 0. -0.03673002 > -0.00282937 > 22 >0.03952920 0. -0.00374183 0.0. > 0. > -0.00374183 0.0.03952920 0.0. > 0. >0. 0.0. 0.0.29542189 > 0. > 23 > -0.04191744 -0.00060.00162178 0.000699500. > 0. >0.00162178 0.00069950 -0.04191744 -0.00060. > 0. >0. 0.0. 0. -0.25545367 > 0.00387305 > 31 > -0.04191744 -0.00060.00162178 0.000699500. > 0. >0.00162178 0.00069950 -0.04191744 -0.00060. > 0. >0. 0.0. 0. -0.25545367 > 0.00387305 > 32 > -0.04191744 0.00060.00162178 -0.000699500. > 0. >0.00162178 -0.00069950 -0.04191744 0.00060. > 0. >0. 0.0. 0. -0.25545367 > -0.00387305 > 33 >0.10704556 0. -0.00739632 0.0. > 0. > -0.00739632 0.0.10704556 0.0. > 0. >0. 0.0. 0.0.54383493 > 0. > > *matdyn.modes:* > > diagonalizing the dynamical matrix ... > > q = 0.5000 0.5000 0.5000 > ** > freq (1) = 1.318544 [THz] = 43.981900 [cm-1] > ( -0.411001 0.032309-0.411001 0.032309 0.00 0.00 ) > ( -0.381067 -0.157332-0.381067 -0.157332 0.00 0.00 ) > ( -0.395193 -0.062378-0.395193 -0.062378 0.00 0.00 ) > freq (2) = 1.662161 [THz] = 55.443739 [cm-1] > ( 0.00 0.00 0.00 0.00 0.578232 0.001810 ) > ( 0.00 0.00 0.00 0.00 0.578232 -0.001810 ) > ( 0.00 0.00 0.00 0.00 0.575577 0.00 ) > freq (3) = 2.140009 [THz] = 71.383008 [cm-1] > ( 0.249628 0.355541-0.249628 -0.355541 0.00 0.00 ) > ( 0.274220 -0.336937-0.274220 0.336937 0.00 0.00 ) > ( 0.349855 0.012425-0.349855 -0.012425 0.00 0.00 ) > freq (4) = 2.763777 [THz] = 92.
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
Dear Sir, Sorry for the eps figure. Now I attached new figure with pdf extension In the mean time, I am following the same definition for LO-TO splitting at Gamma point level. But, I am not clear about the below sentence far from Gamma. "An the end of the dynamical matrix file you have the frequencies and the atom displacements (3 times number of atoms complex numbers). If the displacement for every atom is parallel to the q-point, the mode is Longitudinal; if it is orthogonal, the mode is Transverse. In every other case it is neither. You can then associated the frequency with the label.". I would like to know that is there any possibility to know more details far from Gamma point. Here with I am adding the ip and ops of matdyn.x ( Here I am using only one special point in the IBZ) *Matdyn.in :* &input asr='crystal',q_in_band_form=.true. fleig='matdyn.eig', fldyn='AB22.dyn',flfrc='AB2444_with_ASR.fc', flfrq='AB2_with_ASR.freq' / 1 0.5 0.5 0.5 2 *AB2.dyn* : Dynamical Matrix in cartesian axes q = (0.5 0.5 0.5 ) 11 0.03952920 0. -0.00374183 0.0. 0. -0.00374183 0.0.03952920 0.0. 0. 0. 0.0. 0.0.29542189 0. 12 0.02007831 -0.0009 -0.01131717 0.006725040. 0. -0.01131717 0.006725040.02007831 -0.00090. 0. 0. 0.0. 0. -0.03673002 0.00282937 13 -0.04191744 0.00060.00162178 -0.000699500. 0. 0.00162178 -0.00069950 -0.04191744 0.00060. 0. 0. 0.0. 0. -0.25545367 -0.00387305 21 0.02007831 0.0009 -0.01131717 -0.006725040. 0. -0.01131717 -0.006725040.02007831 0.00090. 0. 0. 0.0. 0. -0.03673002 -0.00282937 22 0.03952920 0. -0.00374183 0.0. 0. -0.00374183 0.0.03952920 0.0. 0. 0. 0.0. 0.0.29542189 0. 23 -0.04191744 -0.00060.00162178 0.000699500. 0. 0.00162178 0.00069950 -0.04191744 -0.00060. 0. 0. 0.0. 0. -0.25545367 0.00387305 31 -0.04191744 -0.00060.00162178 0.000699500. 0. 0.00162178 0.00069950 -0.04191744 -0.00060. 0. 0. 0.0. 0. -0.25545367 0.00387305 32 -0.04191744 0.00060.00162178 -0.000699500. 0. 0.00162178 -0.00069950 -0.04191744 0.00060. 0. 0. 0.0. 0. -0.25545367 -0.00387305 33 0.10704556 0. -0.00739632 0.0. 0. -0.00739632 0.0.10704556 0.0. 0. 0. 0.0. 0.0.54383493 0. *matdyn.modes:* diagonalizing the dynamical matrix ... q = 0.5000 0.5000 0.5000 ** freq (1) = 1.318544 [THz] = 43.981900 [cm-1] ( -0.411001 0.032309-0.411001 0.032309 0.00 0.00 ) ( -0.381067 -0.157332-0.381067 -0.157332 0.00 0.00 ) ( -0.395193 -0.062378-0.395193 -0.062378 0.00 0.00 ) freq (2) = 1.662161 [THz] = 55.443739 [cm-1] ( 0.00 0.00 0.00 0.00 0.578232 0.001810 ) ( 0.00 0.00 0.00 0.00 0.578232 -0.001810 ) ( 0.00 0.00 0.00 0.00 0.575577 0.00 ) freq (3) = 2.140009 [THz] = 71.383008 [cm-1] ( 0.249628 0.355541-0.249628 -0.355541 0.00 0.00 ) ( 0.274220 -0.336937-0.274220 0.336937 0.00 0.00 ) ( 0.349855 0.012425-0.349855 -0.012425 0.00 0.00 ) freq (4) = 2.763777 [THz] = 92.189664 [cm-1] ( -0.043052 0.489305 0.043052 -0.489305 0.00 0.00 ) ( -0.032204 -0.490138 0.032204 0.490138 0.00 0.00 ) ( -0.132110 -0.001463 0.132110 0.001463 0.00 0.00 ) freq (5) = 4.043036 [THz] = 134.861157 [cm-1] ( -0.061283 0.494864-0.061283 0.494864 0.00 0.00 ) ( -0.060611 -0.494947-0.060611 -0.494947 0.00 0.00 ) ( 0.052041 0.35 0.052041 0.35 0.00 0.00 ) freq (6) = 5.972075 [THz] = 199.206984 [cm-1] ( -0.480641 -0.101587
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
Dear Kondaiah, I cannot see the picture you have attached (it looks blank here). Anyway, the way to tell if a mode is Transverse or Longitudinal is to have matdyn save the dynamical matrix for a place next to the Gamma point (e.g. q=[0.01 0. 0.], set the input variable fldyn="filename") An the end of the dynamical matrix file you have the frequencies and the atom displacements (3 times number of atoms complex numbers). If the displacement for every atom is parallel to the q-point, the mode is Longitudinal; if it is orthogonal, the mode is Transverse. In every other case it is neither. You can then associated the frequency with the label. HTH On 20/11/14 15:43, Kondaiah Samudrala wrote: > Dear Dr. Lorenzo Paulatto > > > Thank you for the conformation.. How can I distinguish the both modes.. i.e > whether LO or TO. Because, in the phonon dispersion plot, I observed that my > GAMMA point having two numbers ( pls see the values Gamma-X and M to Gamma > directions...). Here with I am attaching the plot. > > > Please suggest me sir > > > with regards > > S. Appalakondaiah > > PhD Schloar > > University of Hyderabad > > > > > ___ > Pw_forum mailing list > Pw_forum@pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Université Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05 ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
Dear Dr. Lorenzo Paulatto Thank you for the conformation.. How can I distinguish the both modes.. i.e whether LO or TO. Because, in the phonon dispersion plot, I observed that my GAMMA point having two numbers ( pls see the values Gamma-X and M to Gamma directions...). Here with I am attaching the plot. Please suggest me sir with regards S. Appalakondaiah PhD Schloar University of Hyderabad 0-PD.eps Description: PostScript document ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] LO-TO splitting in complete phonon dispersion using PWSCF
The phonon dispersion will automatically include LO-TO splitting, if effective charges are found in the force constants file. kind regards -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Université Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05 ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
