Re: [QE-users] dipole correction - "saggy" electrostatic potential?
Dear Thomas, thank you for your detailed replies which were, as always, very helpful! Best, Chris On Mon, Jul 2, 2018 at 2:57 PM, Dr. Thomas Brumme < thomas.bru...@uni-leipzig.de> wrote: > Dear Chris, > > adding to my last reply: in the end, it all, of course, depends on what > you want to simulate. If you're aiming for a charged species on a surface > then assume_isolated='2D' might be wrong if you don't increase the slab > (mimicking the surface of a bulk material) such that the electric field > at the bottom does not influence the top. It might be worth to also look > at my implementation of a gate setup (gate=.true.) or to wait till the > author of assume_isolated='2D', Thibault Sohier, releases his > implementation > including the gate setup. Gate? Maybe check this paper to see why this > could be useful: > > https://www.sciencedirect.com/science/article/pii/S0169433218315022 > > As I said, it all depends on the situation you want to simulate. But a > flat potential with the same absolute value on both sides of the system > is rarely correct for a charged system. > > > Regards > > Thomas > > Zitat von Christoph Wolf : > > Dear Thomas, >> >> I played a bit with "assume_isolated='2D'" but I do not think that this >> can >> correct the electrostatic potential of charged sytems (in the sense that >> the potential becomes "flat") unless I am interpreting the output >> (attached) wrong. >> >> One way that gives me a flat vacuum potential is to use the M-P scheme but >> that only works for cubic systems. After reading about the implementation >> in VASP a bit I also think that is what they recommend. >> >> Best, >> Chris >> >> On Thu, Jun 28, 2018 at 7:04 PM, Dr. Thomas Brumme < >> thomas.bru...@uni-leipzig.de> wrote: >> >> Dear Chris, >>> >>> The potential shows the typical quadratic dependence on z since you're >>> calculating a charged system - there is a homogeneous background charge >>> since the 3D pbc system is assumed to be neutral. This has nothing to do >>> with the dipole correction. Depending on what you want to do next it >>> might >>> be useful to set the flag assume_isolated='2D' >>> >>> Regards >>> >>> Thomas >>> >>> Zitat von Christoph Wolf : >>> >>> >>> Dear all, >>> I am still observing something strange in my slab + dipole correction calculation that I do not fully understand. When using dipfield+tefield (eopreg and emaxpos well within the vacuum region) I encounter a "saggy" electrostatic potential (plot_num=11) despite the sawtooth efield potential (plot_num=12) looking as usual. Maybe someone can give it a look and confirm if this is due to the excess charge in the system (this does not happen when running the same system in VASP)? I attach input and the plot of the potential for 2 and 4 layers of vacuum (more vacuum does seem to improve the situation). Thank you in advance for your time and assistance! Chris PS: I am using a QE version with dipole bug fix: Program PWSCF v.6.2.2 starts on 25Jun2018 at 10:39:24 -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea >>> -- >>> Dr. rer. nat. Thomas Brumme >>> Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry >>> Leipzig University >>> Phillipp-Rosenthal-Strasse 31 >>> 04103 Leipzig >>> >>> Tel: +49 (0)341 97 36456 >>> >>> email: thomas.bru...@uni-leipzig.de >>> >>> >>> >> >> -- >> Postdoctoral Researcher >> Center for Quantum Nanoscience, Institute for Basic Science >> Ewha Womans University, Seoul, South Korea >> > > > > -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea ___ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
Re: [QE-users] dipole correction - "saggy" electrostatic potential?
M-P = Makov-Payne? I don't think it changes the potential, just the energy Paolo On Mon, Jul 2, 2018 at 4:01 AM, Christoph Wolf wrote: > Dear Thomas, > > I played a bit with "assume_isolated='2D'" but I do not think that this > can correct the electrostatic potential of charged sytems (in the sense > that the potential becomes "flat") unless I am interpreting the output > (attached) wrong. > > One way that gives me a flat vacuum potential is to use the M-P scheme but > that only works for cubic systems. After reading about the implementation > in VASP a bit I also think that is what they recommend. > > Best, > Chris > > On Thu, Jun 28, 2018 at 7:04 PM, Dr. Thomas Brumme < > thomas.bru...@uni-leipzig.de> wrote: > >> Dear Chris, >> >> The potential shows the typical quadratic dependence on z since you're >> calculating a charged system - there is a homogeneous background charge >> since the 3D pbc system is assumed to be neutral. This has nothing to do >> with the dipole correction. Depending on what you want to do next it might >> be useful to set the flag assume_isolated='2D' >> >> Regards >> >> Thomas >> >> Zitat von Christoph Wolf : >> >> >> Dear all, >>> >>> I am still observing something strange in my slab + dipole correction >>> calculation that I do not fully understand. >>> >>> When using dipfield+tefield (eopreg and emaxpos well within the vacuum >>> region) I encounter a "saggy" electrostatic potential (plot_num=11) >>> despite >>> the sawtooth efield potential (plot_num=12) looking as usual. Maybe >>> someone >>> can give it a look and confirm if this is due to the excess charge in the >>> system (this does not happen when running the same system in VASP)? >>> >>> I attach input and the plot of the potential for 2 and 4 layers of vacuum >>> (more vacuum does seem to improve the situation). >>> >>> Thank you in advance for your time and assistance! >>> >>> Chris >>> >>> PS: I am using a QE version with dipole bug fix: >>> >>> Program PWSCF v.6.2.2 starts on 25Jun2018 at 10:39:24 >>> >>> -- >>> Postdoctoral Researcher >>> Center for Quantum Nanoscience, Institute for Basic Science >>> Ewha Womans University, Seoul, South Korea >>> >> >> -- >> Dr. rer. nat. Thomas Brumme >> Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry >> Leipzig University >> Phillipp-Rosenthal-Strasse 31 >> 04103 Leipzig >> >> Tel: +49 (0)341 97 36456 >> >> email: thomas.bru...@uni-leipzig.de >> >> > > > -- > Postdoctoral Researcher > Center for Quantum Nanoscience, Institute for Basic Science > Ewha Womans University, Seoul, South Korea > > > ___ > users mailing list > users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users > -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222 ___ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
Re: [QE-users] dipole correction - "saggy" electrostatic potential?
Dear Chris, adding to my last reply: in the end, it all, of course, depends on what you want to simulate. If you're aiming for a charged species on a surface then assume_isolated='2D' might be wrong if you don't increase the slab (mimicking the surface of a bulk material) such that the electric field at the bottom does not influence the top. It might be worth to also look at my implementation of a gate setup (gate=.true.) or to wait till the author of assume_isolated='2D', Thibault Sohier, releases his implementation including the gate setup. Gate? Maybe check this paper to see why this could be useful: https://www.sciencedirect.com/science/article/pii/S0169433218315022 As I said, it all depends on the situation you want to simulate. But a flat potential with the same absolute value on both sides of the system is rarely correct for a charged system. Regards Thomas Zitat von Christoph Wolf : Dear Thomas, I played a bit with "assume_isolated='2D'" but I do not think that this can correct the electrostatic potential of charged sytems (in the sense that the potential becomes "flat") unless I am interpreting the output (attached) wrong. One way that gives me a flat vacuum potential is to use the M-P scheme but that only works for cubic systems. After reading about the implementation in VASP a bit I also think that is what they recommend. Best, Chris On Thu, Jun 28, 2018 at 7:04 PM, Dr. Thomas Brumme < thomas.bru...@uni-leipzig.de> wrote: Dear Chris, The potential shows the typical quadratic dependence on z since you're calculating a charged system - there is a homogeneous background charge since the 3D pbc system is assumed to be neutral. This has nothing to do with the dipole correction. Depending on what you want to do next it might be useful to set the flag assume_isolated='2D' Regards Thomas Zitat von Christoph Wolf : Dear all, I am still observing something strange in my slab + dipole correction calculation that I do not fully understand. When using dipfield+tefield (eopreg and emaxpos well within the vacuum region) I encounter a "saggy" electrostatic potential (plot_num=11) despite the sawtooth efield potential (plot_num=12) looking as usual. Maybe someone can give it a look and confirm if this is due to the excess charge in the system (this does not happen when running the same system in VASP)? I attach input and the plot of the potential for 2 and 4 layers of vacuum (more vacuum does seem to improve the situation). Thank you in advance for your time and assistance! Chris PS: I am using a QE version with dipole bug fix: Program PWSCF v.6.2.2 starts on 25Jun2018 at 10:39:24 -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea -- Dr. rer. nat. Thomas Brumme Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry Leipzig University Phillipp-Rosenthal-Strasse 31 04103 Leipzig Tel: +49 (0)341 97 36456 email: thomas.bru...@uni-leipzig.de -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea ___ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
Re: [QE-users] dipole correction - "saggy" electrostatic potential?
Dear Chris, The result of assume_isolated='2D' is correct, also physically: The potential of a charged plate increases linearly with the distance from this plate. Check physics books on electrostatics. The wiggles in the center of the vacuum are due to the implementation - since they're in the "nonphysical" region (wave functions are zero) they don't matter. Cheers Thomas Zitat von Christoph Wolf : Dear Thomas, I played a bit with "assume_isolated='2D'" but I do not think that this can correct the electrostatic potential of charged sytems (in the sense that the potential becomes "flat") unless I am interpreting the output (attached) wrong. One way that gives me a flat vacuum potential is to use the M-P scheme but that only works for cubic systems. After reading about the implementation in VASP a bit I also think that is what they recommend. Best, Chris On Thu, Jun 28, 2018 at 7:04 PM, Dr. Thomas Brumme < thomas.bru...@uni-leipzig.de> wrote: Dear Chris, The potential shows the typical quadratic dependence on z since you're calculating a charged system - there is a homogeneous background charge since the 3D pbc system is assumed to be neutral. This has nothing to do with the dipole correction. Depending on what you want to do next it might be useful to set the flag assume_isolated='2D' Regards Thomas Zitat von Christoph Wolf : Dear all, I am still observing something strange in my slab + dipole correction calculation that I do not fully understand. When using dipfield+tefield (eopreg and emaxpos well within the vacuum region) I encounter a "saggy" electrostatic potential (plot_num=11) despite the sawtooth efield potential (plot_num=12) looking as usual. Maybe someone can give it a look and confirm if this is due to the excess charge in the system (this does not happen when running the same system in VASP)? I attach input and the plot of the potential for 2 and 4 layers of vacuum (more vacuum does seem to improve the situation). Thank you in advance for your time and assistance! Chris PS: I am using a QE version with dipole bug fix: Program PWSCF v.6.2.2 starts on 25Jun2018 at 10:39:24 -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea -- Dr. rer. nat. Thomas Brumme Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry Leipzig University Phillipp-Rosenthal-Strasse 31 04103 Leipzig Tel: +49 (0)341 97 36456 email: thomas.bru...@uni-leipzig.de -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea ___ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
Re: [QE-users] dipole correction - "saggy" electrostatic potential?
Dear Thomas, I played a bit with "assume_isolated='2D'" but I do not think that this can correct the electrostatic potential of charged sytems (in the sense that the potential becomes "flat") unless I am interpreting the output (attached) wrong. One way that gives me a flat vacuum potential is to use the M-P scheme but that only works for cubic systems. After reading about the implementation in VASP a bit I also think that is what they recommend. Best, Chris On Thu, Jun 28, 2018 at 7:04 PM, Dr. Thomas Brumme < thomas.bru...@uni-leipzig.de> wrote: > Dear Chris, > > The potential shows the typical quadratic dependence on z since you're > calculating a charged system - there is a homogeneous background charge > since the 3D pbc system is assumed to be neutral. This has nothing to do > with the dipole correction. Depending on what you want to do next it might > be useful to set the flag assume_isolated='2D' > > Regards > > Thomas > > Zitat von Christoph Wolf : > > > Dear all, >> >> I am still observing something strange in my slab + dipole correction >> calculation that I do not fully understand. >> >> When using dipfield+tefield (eopreg and emaxpos well within the vacuum >> region) I encounter a "saggy" electrostatic potential (plot_num=11) >> despite >> the sawtooth efield potential (plot_num=12) looking as usual. Maybe >> someone >> can give it a look and confirm if this is due to the excess charge in the >> system (this does not happen when running the same system in VASP)? >> >> I attach input and the plot of the potential for 2 and 4 layers of vacuum >> (more vacuum does seem to improve the situation). >> >> Thank you in advance for your time and assistance! >> >> Chris >> >> PS: I am using a QE version with dipole bug fix: >> >> Program PWSCF v.6.2.2 starts on 25Jun2018 at 10:39:24 >> >> -- >> Postdoctoral Researcher >> Center for Quantum Nanoscience, Institute for Basic Science >> Ewha Womans University, Seoul, South Korea >> > > -- > Dr. rer. nat. Thomas Brumme > Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry > Leipzig University > Phillipp-Rosenthal-Strasse 31 > 04103 Leipzig > > Tel: +49 (0)341 97 36456 > > email: thomas.bru...@uni-leipzig.de > > -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea plot.pdf Description: Adobe PDF document ___ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
Re: [QE-users] dipole correction - "saggy" electrostatic potential?
Dear Thomas, thank you for your explanation. I am now curious why this does not seem to effect my VASP calculation but I guess I have to ascribed it to different implementations of either the dipole correction or how the background is treated... AS VASP only allows to charge "cubic cells" I guess they implement the m-p scheme: I will try assume_isolated='2D' and 'mp' and see if I can reproduce the VASP results! Thank you again for your help! Chris On Thu, Jun 28, 2018 at 7:04 PM, Dr. Thomas Brumme < thomas.bru...@uni-leipzig.de> wrote: > Dear Chris, > > The potential shows the typical quadratic dependence on z since you're > calculating a charged system - there is a homogeneous background charge > since the 3D pbc system is assumed to be neutral. This has nothing to do > with the dipole correction. Depending on what you want to do next it might > be useful to set the flag assume_isolated='2D' > > Regards > > Thomas > > Zitat von Christoph Wolf : > > > Dear all, >> >> I am still observing something strange in my slab + dipole correction >> calculation that I do not fully understand. >> >> When using dipfield+tefield (eopreg and emaxpos well within the vacuum >> region) I encounter a "saggy" electrostatic potential (plot_num=11) >> despite >> the sawtooth efield potential (plot_num=12) looking as usual. Maybe >> someone >> can give it a look and confirm if this is due to the excess charge in the >> system (this does not happen when running the same system in VASP)? >> >> I attach input and the plot of the potential for 2 and 4 layers of vacuum >> (more vacuum does seem to improve the situation). >> >> Thank you in advance for your time and assistance! >> >> Chris >> >> PS: I am using a QE version with dipole bug fix: >> >> Program PWSCF v.6.2.2 starts on 25Jun2018 at 10:39:24 >> >> -- >> Postdoctoral Researcher >> Center for Quantum Nanoscience, Institute for Basic Science >> Ewha Womans University, Seoul, South Korea >> > > -- > Dr. rer. nat. Thomas Brumme > Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry > Leipzig University > Phillipp-Rosenthal-Strasse 31 > 04103 Leipzig > > Tel: +49 (0)341 97 36456 > > email: thomas.bru...@uni-leipzig.de > > -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea ___ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
Re: [QE-users] dipole correction - "saggy" electrostatic potential?
Dear Chris, The potential shows the typical quadratic dependence on z since you're calculating a charged system - there is a homogeneous background charge since the 3D pbc system is assumed to be neutral. This has nothing to do with the dipole correction. Depending on what you want to do next it might be useful to set the flag assume_isolated='2D' Regards Thomas Zitat von Christoph Wolf : Dear all, I am still observing something strange in my slab + dipole correction calculation that I do not fully understand. When using dipfield+tefield (eopreg and emaxpos well within the vacuum region) I encounter a "saggy" electrostatic potential (plot_num=11) despite the sawtooth efield potential (plot_num=12) looking as usual. Maybe someone can give it a look and confirm if this is due to the excess charge in the system (this does not happen when running the same system in VASP)? I attach input and the plot of the potential for 2 and 4 layers of vacuum (more vacuum does seem to improve the situation). Thank you in advance for your time and assistance! Chris PS: I am using a QE version with dipole bug fix: Program PWSCF v.6.2.2 starts on 25Jun2018 at 10:39:24 -- Postdoctoral Researcher Center for Quantum Nanoscience, Institute for Basic Science Ewha Womans University, Seoul, South Korea -- Dr. rer. nat. Thomas Brumme Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry Leipzig University Phillipp-Rosenthal-Strasse 31 04103 Leipzig Tel: +49 (0)341 97 36456 email: thomas.bru...@uni-leipzig.de ___ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
