Re: [Wien] Spontaneous polarization of PbTiO3

Dear Gavin, Now I have used the same tetragonal structure with centrosymmetric atomic positions. The polarization calculated with the centrosymmetric structure is in an order of e-13. So it didn't modify the results significantly. I am attaching the currently used centrosymmetric,

Re: [Wien] Spontaneous polarization of PbTiO3

Dear Gavin, This is a very good point. I certainly agree that the symmetry of the cubic structure should be reduced to that of the tetragonal structure. Thank you  Oleg  On May 8, 2018, at 04:05, Gavin Abo wrote: In the BaTiO3 tutorial, lambda1.struct and

Re: [Wien] Spontaneous polarization of PbTiO3

In the BaTiO3 tutorial, lambda1.struct and lambda0.struct both have spacegroup 99_P4mm and 8 symmetry operations [ https://github.com/spichardo/BerryPI/wiki/Tutorial-1:-Spontaneous-Polarization-in-BaTiO3 ]. I see a sentence in the tutorial: /The symmetry operations are identical (!) to the

Re: [Wien] Spontaneous polarization of PbTiO3

Dear Lokanath, I am traveling and will be able to look into this at the end of May. In the meanwhile would you please share a comparison of your PbTiO3 structure vs experiments through the list. Thank you Oleg > On May 7, 2018, at 13:36, Lokanath Patra wrote:

Re: [Wien] Spontaneous polarization of PbTiO3

Dear Oleg, I am attaching the structure files which I have used for the calculation. I have used similar procedure as given for BaTiO3 tutorial (same parameters for initialising and same k-point mesh for Berrypi. The calculated polarisation for cubic phase is very low. So so spontaneous

Re: [Wien] Spontaneous polarization of PbTiO3

Dear Lokanath, PbTiO3 was one of compounds used in the test of BerryPI (see Table 3 in http://olegrubel.mcmaster.ca/publications/2013/Ahmed_CPC_184_2013.pdf). I think you should also compute polarization in the cubic structure of PbTiO3 even though they are deemed to have no polarization. If

[Wien] Spontaneous polarization of PbTiO3

Dear all, I am using Berry phase tutorial to calculate the polarization of PbTiO3. I have followed the BaTiO3 tutorial. I have two structures, one is tetragonal (non-centrosymmetric) and the second one is cubic (centrosymmetric). I have calculated the (spontaneous) polarization as 1.189769e-01