Dear Prof. Marks, Thank you very much for the conceptual reply.
I am unable to answer the second point now but please see for 1st and 3rd point: I agree that some time hybrid calculations may fail for some systems. May you also want to point out that with element from high Z a -SO correction is needed. But in some reputed papers (Nano. letters) it is mention that -SO does not affect much for my system. Regarding, PBESol: in two of PRB papers of Prof. Peter, it is mentioned that PBESol and WC-GGA are better for optimization "PhysRevB.79.155107.pdf", PHYSICAL REVIEW B 79, 085104 2009 . The same trend I am getting where LDA is underestimating the lattice parameter optimization and PBE is overestimating for a list of materials that I have testes. WC-GGA and PBESol are giving the optimized lattice parameters in the vicinity of Exp lattice parameters (~0.01-~0.02 Ang reduced). So I used PBESol with mBJ. Yes, I also do agree that according to UG, LDA or PBE are good for mBJ but as PBESol gave me well-optimized results so I used PBESol with mBJ. So I am not able to find out the solution to my issue; Why the bandgap is drastically reducing if I use "double relaxed structure": 1. relaxed>> 2. optimization of lattice parameter without relaxing>>> 3. again relaxing the structure (using relaxed structure from step 1 and optimized lattice parameter from step 2.). I am sure the procedure used above seems wrong but I am not able to justify the "double relaxation of the structure. regards, Bhamu On Thu, Feb 8, 2018 at 6:48 PM, Laurence Marks <[email protected]> wrote: > Inlined, please think: > > On Feb 8, 2018 7:08 AM, "Dr. K. C. Bhamu" <[email protected]> wrote: > > Dear Prof. Marks, > > I believe I am having to understand about the mentioned points: > > > 1) Why is your number for the band gap "wrong", whereas what someone else > calculated with HSE is "right"? > > Ans: Maybe you want to ask me why the band gap from my calculations should > be fine instead of HSE. If so, then I shall mention that hybrid > calculations are already a well know approach to predict the band gap of > inorganic systems. > > > Does that mean HSE is right? > > > 2) What is the purpose of optimizing internal and cell parameters? > > Ans: To get the minimum forces on the system and by doing total > optimization the system would be in the most stable ground state and can > give accurate properties if the most suitable approach is applied!! > > > Why? > > > 3) Are the cell and internal parameters of PBEsol the same as what they > should be with mBJ? What does "should be" mean here? > > Ans: Yes, structure file is same for PBESol and mBJ. According to me you > wanted to ask me whether I have applied any changes in mBJ calculation, > like relaxation (which is not possible and I did not apply). > I just did PBESol scf >> save_lapw case_scf>>> one scf cycle>> save_lapw > mbjx_grr >>> spacified the mBJ approach and finally mBJ scf. > > Why should a PBEsol refined structure be optimal for mBJ? > > > regards > Bhamu > > > On Feb 8, 2018 3:41 AM, "Dr. K. C. Bhamu" <[email protected]> wrote: > > No, I said the calculated gal is ~0.3eV less then the reported gap: HSE. > > > I tested this on more than 10 systems and in each case obsessed this band > gap discrepancy. > > Regards > Bhamu > > On Feb 8, 2018 3:05 PM, <[email protected]> wrote: > >> A band gap of 0.3 eV is very small and a change of lattice constant may >> be enough to close the band gap. >> >> On Thursday 2018-02-08 10:30, Dr. K. C. Bhamu wrote: >> >> Date: Thu, 8 Feb 2018 10:30:29 >>> From: Dr. K. C. Bhamu <[email protected]> >>> Reply-To: A Mailing list for WIEN2k users <[email protected]. >>> at> >>> To: A Mailing list for WIEN2k users <[email protected]> >>> Subject: Re: [Wien] a note on lattice parameter optimization >>> >>> Yes, I used PBESol followed by mBJ. >>> >>> On Feb 8, 2018 2:28 PM, <[email protected]> wrote: >>> Hi, >>> >>> Did you use mBJ to calculate the band gap in both procedures? >>> >>> FT >>> >>> On Thursday 2018-02-08 09:35, Dr. K. C. Bhamu wrote: >>> >>> Date: Thu, 8 Feb 2018 09:35:08 >>> From: Dr. K. C. Bhamu <[email protected]> >>> Reply-To: A Mailing list for WIEN2k users < >>> [email protected]> >>> To: A Mailing list for WIEN2k users < >>> [email protected]> >>> Subject: [Wien] a note on lattice parameter optimization >>> >>> Hello, >>> >>> Using experimental lattice parameters(a Ang), I optimized the >>> structure with two options. >>> >>> 1. Directly optimized the structure without min_lapw ... and >>> the optimized lattice parameters are in the vicinity of Exp a (~0.01 Ang >>> accuracy) and the calculated band gap (from mBJ2) is in agreement with >>> reported value ~0.3 eV less. >>> >>> 2. First relaxed the structure and then optimized this >>> relaxed structure (without min_lapw ....). In this case the optimized >>> lattice parameters are reduced by ~0.05 Ang and the band gap vanished or >>> largely reduced. >>> >>> >>> Why is the second way of doing band structure not working? >>> >>> I tested it on many systems. In some case system became metal >>> and in some cases band gap largely reduced when I used the fully relaxed >>> structure for optimization. >>> >>> >>> Thanks, >>> >>> >>> Bhamu >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> Wien mailing list >>> [email protected] >>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=jl0lHi-CtjMpp__lsTB6ZTdAJ0Xy47bf44CPXSBt7QE&s=xezPeLzVIzkyNQZdVyrkfiQm7d4wtaXeocIv-y-KdUY&e=> >>> SEARCH the MAILING-LIST at: http://www.mail-archive.com/wi >>> [email protected]/index.html >>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=jl0lHi-CtjMpp__lsTB6ZTdAJ0Xy47bf44CPXSBt7QE&s=1EhCR6okBj_tGDzqdgSAxNSZftNyujAJxvs8z3T7sq4&e=> >>> >>> >>> >> _______________________________________________ >> Wien mailing list >> [email protected] >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=jl0lHi-CtjMpp__lsTB6ZTdAJ0Xy47bf44CPXSBt7QE&s=xezPeLzVIzkyNQZdVyrkfiQm7d4wtaXeocIv-y-KdUY&e=> >> SEARCH the MAILING-LIST at: http://www.mail-archive.com/wi >> [email protected]/index.html >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=jl0lHi-CtjMpp__lsTB6ZTdAJ0Xy47bf44CPXSBt7QE&s=1EhCR6okBj_tGDzqdgSAxNSZftNyujAJxvs8z3T7sq4&e=> >> >> > >> _______________________________________________ >> Wien mailing list >> [email protected] >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=aQoRvD9xu6e3OubdKBDmPnflUbmo41M7nwDfegZLBrg&s=1Y5DBgtCcLyu85SWwEL5PbwOT8-nRgYp67SVCwRNdgk&e=> >> SEARCH the MAILING-LIST at: http://www.mail-archive.com/wi >> [email protected]/index.html >> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=aQoRvD9xu6e3OubdKBDmPnflUbmo41M7nwDfegZLBrg&s=CQF8_t9GbaY-SgmuduDNbdIs1KsKQPhsf3uKTaKSE_Y&e=> >> >> > > > _______________________________________________ > Wien mailing list > [email protected] > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: http://www.mail-archive.com/ > [email protected]/index.html > >
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