Re: [Wien] Born effective charge in GaN
Hello Shahrbano, I was able to compute the Effective charge of GaN using the structure files provided by Dr. Rubel. This is how it looks, Z=(1.76267778062-1.7075251678616241)/0.02 Z=2.7576306379187954 My computed effective charge seems to almost the same as computed by Dr. Rubel. I think you are using older versions of either BerryPI or Wien2Wannier or both. Please use the latest version of BerryPI (v1.0) https://github.com/spichardo/BerryPI and Wien2Wannier (v0.97) http://www.wien2k.at/reg_user/unsupported/wien2wannier/. The older version of BerryPI (v0.1) had some problem in wrapping of phases which has been fixed in version 1.0. Also, the older versions of Wien2wannier was having an issue in identifying the complex calculation (see the post http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac. at/msg09119.html) Regards Sheikh On Mon, Nov 4, 2013 at 5:13 PM, Oleg Rubel oru...@lakeheadu.ca wrote: Dear Shahrbano, I was able to obtain the effective charge of Z(Ga) = 2.76 Here is the approach: 1) Take the structure files enclosed (I assume they are not different from yours). 2) create directories 'lambda1' and 'lambda2'. In both cases I displace the Ga atom by +0.01 and -0.01 along z-axis. There is nothing specific about the choice of displacements. In fact 0.005 should work too. I encourage you to test the convergence and plot Z as a function of displacement. I do not recommend to go for displacements larger than 0.01 3) initialize both using 'init_lapw -b -vxc 13 -ecut -6 -numk 230' 4) rum wien2k 'run_lapw' 5) run berrypi 'berrypi -p$(pwd) -k6:6:4'. You should obtain the output as shown below. 6) Z = (1.7626777806241982 - 1.7075447765644145)/(0.01+0.01) = 2.76 (see Eq. 14 in http://www.tbrri.com/~orubel/publications/2013/Ahmed_CPC_ 184_2013.pdf) The result really close to Vanderbilt. Good sign :) In order to address the spontaneous polarization, we need two cases: (a) the initial reference structure and (b) your relaxed structure. The spontaneous polarization is the difference between them. Please, look in the literature what is used as a reference structure. The choice of structure (a) for GaN is not obvious to me. Once you determine that, I can help you to move on. Thank you Oleg +++ ---PHASES/2*PI IN [0 to 2]RANGE--- IONIC PHASE/(2*PI): [6.010209219198259e-08, 1.999400510458, 0.8898641300788697] ELECTRONIC PHASE/(2*PI): [2.35665164408, -3.5664951224354753e-05, 0.87281365054532878] TOTAL PHASE/(2*PI): [3.572526650019725e-05, 1.642750998212, 1.7626777806241982] ---POLARIZATION IN C/m^2 FOR [0 to 2] PHASE/2PI RANGE--- IONIC POLARIZATION:[6.734131068339737e-08, 2.2408973201721545, 1.6229398446248238] ELECTRONIC POLARIZATION:[2.2409373483287527, -3.9960748009166113e-05, 1.5918430719045986] TOTAL POLARIZATION:[4.0028328181192241e-05, 2.2408573594241452, 3.2147829165294222] ---PHASES/2*PI IN [-1 to +1]RANGE--- IONIC PHASE/(2*PI):[6.010209219198259e-08, -5.994895424521474e-08, 0.8898641300788697] ELECTRONIC PHASE/(2*PI):[3.5665164408005268e-05, -3.5664951224312347e-05, 0.87281365054532878] TOTAL PHASE/(2*PI):[3.572526650019725e-05, -3.5724900178779606e-05, -0.23732221937580178] ---POLARIZATION IN C/m^2 FOR [-1 to +1] PHASE/2PI RANGE--- IONIC POLARIZATION:[6.734131068339736e-08, -6.716972747098987e-08, 1.6229398446248238] ELECTRONIC POLARIZATION:[3.9960986870508846e-05, -3.9960748009118604e-05, 1.5918430719045986] TOTAL POLARIZATION:[4.0028328181192241e-05, -4.0027917736838375e-05, -0.432829768973433] + ---PHASES/2*PI IN [0 to 2]RANGE--- IONIC PHASE/(2*PI): [6.010209219198259e-08, 1.999400510458, 0.6298641300758288] ELECTRONIC PHASE/(2*PI): [-2.9599378548340341e-05, 2.295996358957, 1.0776806464885857] TOTAL PHASE/(2*PI): [1.704607235438, 2.9539686940971421e-05, 1.7075447765644145] ---POLARIZATION IN C/m^2 FOR [0 to 2] PHASE/2PI RANGE--- IONIC POLARIZATION:[6.734131068339737e-08, 2.2408973201721545, 1.1487501955039068] ELECTRONIC POLARIZATION:[-3.3164585027959612e-05, 2.2409305522152549, 1.9654807985263416] TOTAL POLARIZATION:[2.2408642900981648, 3.3097703644459985e-05, 3.1142309940302484] ---PHASES/2*PI IN [-1 to +1]RANGE--- IONIC PHASE/(2*PI):[6.010209219198259e-08, -5.994895424521474e-08, 0.6298641300758288] ELECTRONIC PHASE/(2*PI):[-2.9599378548406108e-05, 2.9599635895660725e-05, -0.92231935351141425] TOTAL PHASE/(2*PI):
[Wien] Born effective charge in GaN
Dear Shahrbano, I was able to obtain the effective charge of Z(Ga) = 2.76 Here is the approach: 1) Take the structure files enclosed (I assume they are not different from yours). 2) create directories 'lambda1' and 'lambda2'. In both cases I displace the Ga atom by +0.01 and -0.01 along z-axis. There is nothing specific about the choice of displacements. In fact 0.005 should work too. I encourage you to test the convergence and plot Z as a function of displacement. I do not recommend to go for displacements larger than 0.01 3) initialize both using 'init_lapw -b -vxc 13 -ecut -6 -numk 230' 4) rum wien2k 'run_lapw' 5) run berrypi 'berrypi -p$(pwd) -k6:6:4'. You should obtain the output as shown below. 6) Z = (1.7626777806241982 - 1.7075447765644145)/(0.01+0.01) = 2.76 (see Eq. 14 in http://www.tbrri.com/~orubel/publications/2013/Ahmed_CPC_184_2013.pdf) The result really close to Vanderbilt. Good sign :) In order to address the spontaneous polarization, we need two cases: (a) the initial reference structure and (b) your relaxed structure. The spontaneous polarization is the difference between them. Please, look in the literature what is used as a reference structure. The choice of structure (a) for GaN is not obvious to me. Once you determine that, I can help you to move on. Thank you Oleg +++ ---PHASES/2*PI IN [0 to 2]RANGE--- IONIC PHASE/(2*PI): [6.010209219198259e-08, 1.999400510458, 0.8898641300788697] ELECTRONIC PHASE/(2*PI): [2.35665164408, -3.5664951224354753e-05, 0.87281365054532878] TOTAL PHASE/(2*PI): [3.572526650019725e-05, 1.642750998212, 1.7626777806241982] ---POLARIZATION IN C/m^2 FOR [0 to 2] PHASE/2PI RANGE--- IONIC POLARIZATION:[6.734131068339737e-08, 2.2408973201721545, 1.6229398446248238] ELECTRONIC POLARIZATION:[2.2409373483287527, -3.9960748009166113e-05, 1.5918430719045986] TOTAL POLARIZATION:[4.0028328181192241e-05, 2.2408573594241452, 3.2147829165294222] ---PHASES/2*PI IN [-1 to +1]RANGE--- IONIC PHASE/(2*PI):[6.010209219198259e-08, -5.994895424521474e-08, 0.8898641300788697] ELECTRONIC PHASE/(2*PI):[3.5665164408005268e-05, -3.5664951224312347e-05, 0.87281365054532878] TOTAL PHASE/(2*PI):[3.572526650019725e-05, -3.5724900178779606e-05, -0.23732221937580178] ---POLARIZATION IN C/m^2 FOR [-1 to +1] PHASE/2PI RANGE--- IONIC POLARIZATION:[6.734131068339736e-08, -6.716972747098987e-08, 1.6229398446248238] ELECTRONIC POLARIZATION:[3.9960986870508846e-05, -3.9960748009118604e-05, 1.5918430719045986] TOTAL POLARIZATION:[4.0028328181192241e-05, -4.0027917736838375e-05, -0.432829768973433] + ---PHASES/2*PI IN [0 to 2]RANGE--- IONIC PHASE/(2*PI): [6.010209219198259e-08, 1.999400510458, 0.6298641300758288] ELECTRONIC PHASE/(2*PI): [-2.9599378548340341e-05, 2.295996358957, 1.0776806464885857] TOTAL PHASE/(2*PI): [1.704607235438, 2.9539686940971421e-05, 1.7075447765644145] ---POLARIZATION IN C/m^2 FOR [0 to 2] PHASE/2PI RANGE--- IONIC POLARIZATION:[6.734131068339737e-08, 2.2408973201721545, 1.1487501955039068] ELECTRONIC POLARIZATION:[-3.3164585027959612e-05, 2.2409305522152549, 1.9654807985263416] TOTAL POLARIZATION:[2.2408642900981648, 3.3097703644459985e-05, 3.1142309940302484] ---PHASES/2*PI IN [-1 to +1]RANGE--- IONIC PHASE/(2*PI):[6.010209219198259e-08, -5.994895424521474e-08, 0.6298641300758288] ELECTRONIC PHASE/(2*PI):[-2.9599378548406108e-05, 2.9599635895660725e-05, -0.92231935351141425] TOTAL PHASE/(2*PI):[-2.9539276456214125e-05, 2.9539686940971421e-05, -0.2924552234355855] ---POLARIZATION IN C/m^2 FOR [-1 to +1] PHASE/2PI RANGE--- IONIC POLARIZATION:[6.734131068339736e-08, -6.716972747098987e-08, 1.1487501955039066] ELECTRONIC POLARIZATION:[-3.3164585028033304e-05, 3.3164873372428553e-05, -1.6821318869765136] TOTAL POLARIZATION:[-3.3097243717349902e-05, 3.3097703644459985e-05, -0.53338169147260672] +++ On 04/11/2013 3:35 AM, Shahrbano Raheme wrote: Dear Prof Oleg Rubel,__ I went trough tutorials 1 and 2 of the BerryPI, and could reproduce the results without any problems. But, now I would like to calculate the spontaneous polarization for the GaN __ structure. For sure, GaN.struct is pasted at the end of this e-mail. I have done these steps; 1.I relaxed the system 2.init_lapw 3.run_lapw 4.Run BerryPI using
