Re: [Wien] Few questions about onsite hybrids and so
Dear prof. Blaha, wow, thanks a lot for such a detailed answer. This was very helpful indeed. Best regards Pavel "Hi, Here are my comments. Most of them similar to what Laurence said. > I'm trying to calculate a band structure of Tb3Ga5O12 magneto-optical > crystal (cubic Ia-3d, 80 atoms). While I consider myself quite > > Luckily I'm not shooting completely blind as I have some high-quality > optical data where we can see some (very weak but also quite sharp and > hence noticeable f-f transitions in the band gap so I have some idea > how the Tb f states at least should look like). Significant optical > absorption start around 4eV but below that I see some very weak > electronic transitions in the 0.2-0.9eV range, around 2.5 and 3.5eV > (reportedly between f states located in the band gap). So I expect at > least three bunches of f states in band gap one occupied and the others > unoccupied. Unfortunately, I don't believe that these optical f-f transitions can be described by DFT. These are crystal-field splitted multiplet excitations, which are usually not accessible by DFT. PS: Optical transitions create an electron-hole pair and excitonic (correlation) effects can be very large. XPS creates a free electron and a hole and although this is also not a ground state, it is usually better described by groundstate DFT. >From your chemical formulae one expects Tb3+, i.e. a fully occupied spin-up 4f band and a single 4f electron occupied in spin-dn. Of course, PBE gives a metal and the 4f-dn states are pinned at EF. An orbital potential can split these states and single out a single 4f electron/atom. However, with orbital potentials in many cases one can obtain several different orbitals occupied, which depends on the starting density matrix. In other words, your solution may not be the ground state, but a metastable state. Therefor I'd do first GGA+SO, and "hope" that this gives me a bit larger occupancy of the "correct" 4f orbital. When you then calculate the density matrix from this solution, you may run in the lowest energy orbitally-ordered state. Eventually, you could also start from different density matrices and see to which solutions you converge and compare total energies (these manipulations are simpler in DFT+U than in EECE). RMTs: Since we cannot use HDLOs for orbital potentials, too large spheres are not good. However, (in particular for 3d systems) small spheres mean that only 80-90% of the d-charge is inside the sphere and thus gets shifted by the orbital potential. Thus one needs a larger U (or alpha) to get similar results with smaller RMTs. For later 4f atoms, however, the 4f are very localized (in Tb with RMT=2.0 97% of the 4f charge is inside spheres (see case.outputst). My personal choice would be RMT = 2.1 to 2.2). Relaxation: Yes, you can safely relax the O atoms when SO is switched off for them and the heavy atoms are fixed in case.inM. If this is just a powder X-ray structure, the O-positions could be quite wrong. Most 4f systems would be anti-ferromagnets, but with very low Neel temperature, which means that the energy difference between an AFM and FM ordering is very small. These are local moments and they do not care too much how their neighbors are polarized. > > Regarding the f electron correction I opted for onsite hybrid and > initialized it with init_orb_lapw -eece. > UG says that its better to use LDA for the exchange potential so I > copied case.in0 to case.in0eece_lapw where I replaced "XC_PBE" on the > first line with "EX_PBE VX_LDA EC_PBE VC_PBE". This is a misunderstanding. I'd use PBE in case.in0 since the Ga/O states should be much better described by PBE. However, for the double counting correction, LDA is numerically preferred and the UG says: "This is possible by copying case.in0 to case.in0eece_lda and specify VX_LDA". Note: it is case.in0eece_lda, not case.in0eece_lapw EECE vs DFT+U is a matter of taste. EECE has one adjustable parameter, DFT+U 1-2 (U and J). For 4f systems the "effective U" (J=0) is often not justified since the intraatomic J may be important. It may have quite some influence on the orbital magnetic moment. Anyway, both are approximations and for a proper gap you may need mBJ+U (or mBJ+EECE) with a smaller U (alpha). > The onsite hybrid calculation converged fine, I get a nice splitting of > the f states (albeit a bit too much maybe). > The other options would be +U obviously, I went for the hybrid because > it felt more rigorous, but I would also appreciate comments if someone > has maybe better experience with +U? > > Next step was to initialize spin-orbit interaction with init_so_lapw. I > started with the default 001 but I want to also try other directions > later and compare. I opted for no relativistic LOs (no support in > optics) and enabled it only for Tb and Ga. symetso created a new > structure (most notable I have more Tb inequivalent positions) and than > I manually fixed case.inso case.indm and
Re: [Wien] Few questions about onsite hybrids and so
Hi, Here are my comments. Most of them similar to what Laurence said. I'm trying to calculate a band structure of Tb3Ga5O12 magneto-optical crystal (cubic Ia-3d, 80 atoms). While I consider myself quite Luckily I'm not shooting completely blind as I have some high-quality optical data where we can see some (very weak but also quite sharp and hence noticeable f-f transitions in the band gap so I have some idea how the Tb f states at least should look like). Significant optical absorption start around 4eV but below that I see some very weak electronic transitions in the 0.2-0.9eV range, around 2.5 and 3.5eV (reportedly between f states located in the band gap). So I expect at least three bunches of f states in band gap one occupied and the others unoccupied. Unfortunately, I don't believe that these optical f-f transitions can be described by DFT. These are crystal-field splitted multiplet excitations, which are usually not accessible by DFT. PS: Optical transitions create an electron-hole pair and excitonic (correlation) effects can be very large. XPS creates a free electron and a hole and although this is also not a ground state, it is usually better described by groundstate DFT. From your chemical formulae one expects Tb3+, i.e. a fully occupied spin-up 4f band and a single 4f electron occupied in spin-dn. Of course, PBE gives a metal and the 4f-dn states are pinned at EF. An orbital potential can split these states and single out a single 4f electron/atom. However, with orbital potentials in many cases one can obtain several different orbitals occupied, which depends on the starting density matrix. In other words, your solution may not be the ground state, but a metastable state. Therefor I'd do first GGA+SO, and "hope" that this gives me a bit larger occupancy of the "correct" 4f orbital. When you then calculate the density matrix from this solution, you may run in the lowest energy orbitally-ordered state. Eventually, you could also start from different density matrices and see to which solutions you converge and compare total energies (these manipulations are simpler in DFT+U than in EECE). RMTs: Since we cannot use HDLOs for orbital potentials, too large spheres are not good. However, (in particular for 3d systems) small spheres mean that only 80-90% of the d-charge is inside the sphere and thus gets shifted by the orbital potential. Thus one needs a larger U (or alpha) to get similar results with smaller RMTs. For later 4f atoms, however, the 4f are very localized (in Tb with RMT=2.0 97% of the 4f charge is inside spheres (see case.outputst). My personal choice would be RMT = 2.1 to 2.2). Relaxation: Yes, you can safely relax the O atoms when SO is switched off for them and the heavy atoms are fixed in case.inM. If this is just a powder X-ray structure, the O-positions could be quite wrong. Most 4f systems would be anti-ferromagnets, but with very low Neel temperature, which means that the energy difference between an AFM and FM ordering is very small. These are local moments and they do not care too much how their neighbors are polarized. Regarding the f electron correction I opted for onsite hybrid and initialized it with init_orb_lapw -eece. UG says that its better to use LDA for the exchange potential so I > copied case.in0 to case.in0eece_lapw where I replaced "XC_PBE" on the > first line with "EX_PBE VX_LDA EC_PBE VC_PBE". This is a misunderstanding. I'd use PBE in case.in0 since the Ga/O states should be much better described by PBE. However, for the double counting correction, LDA is numerically preferred and the UG says: "This is possible by copying case.in0 to case.in0eece_lda and specify VX_LDA". Note: it is case.in0eece_lda, not case.in0eece_lapw EECE vs DFT+U is a matter of taste. EECE has one adjustable parameter, DFT+U 1-2 (U and J). For 4f systems the "effective U" (J=0) is often not justified since the intraatomic J may be important. It may have quite some influence on the orbital magnetic moment. Anyway, both are approximations and for a proper gap you may need mBJ+U (or mBJ+EECE) with a smaller U (alpha). The onsite hybrid calculation converged fine, I get a nice splitting of the f states (albeit a bit too much maybe). The other options would be +U obviously, I went for the hybrid because it felt more rigorous, but I would also appreciate comments if someone has maybe better experience with +U? Next step was to initialize spin-orbit interaction with init_so_lapw. I started with the default 001 but I want to also try other directions later and compare. I opted for no relativistic LOs (no support in optics) and enabled it only for Tb and Ga. symetso created a new structure (most notable I have more Tb inequivalent positions) and than I manually fixed case.inso case.indm and case.inorb as the init_so script warned me. I also guessed I should fix case.ineece (that seemed straightforward) but than I thought I should also
Re: [Wien] Few questions about onsite hybrids and so
On Mon, 2024-02-12 at 20:57 +0800, Laurence Marks wrote: > With an RMT for Tb of 2.43 the O2p will leak into the Tb sphere. I > used 2.02. You may want to use -ecut .995 or simioar rather than a > fixed energy. Will try, thanks. > If your Ga & Tb positions are fixed then I guess -so might work in > MSR1a, I have never tried. > > N.B., I meant x-ray or neutron positions, the latter might be better > for the O. In my opinion you should not use peaks in spectra or band > gaps as these are excited state properties, and -eece is ground > state. That said, optimizing the hybrid fraction for positions gave > decent gaps for a few other cases as well. Never published as I have > no explanation. I fully agree that comparing band structure to optical spectra (and optical band gaps) is tricky (unless one can also do BSE). However on the contrary I have some good experience with XPS valence band measurements. For example I previously observed good agreement between position of some occupied defect states in the band gap as calculated with (full hybrid) DFT and observed by valence band XPS. Anyway, thanks again for all the suggestions, I'll also check if I can get good enough O positions from XRD to compare to the relaxed positions as dependent on the the hybrid fraction... Best regards Pavel ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
Re: [Wien] Few questions about onsite hybrids and so
With an RMT for Tb of 2.43 the O2p will leak into the Tb sphere. I used
2.02. You may want to use -ecut .995 or simioar rather than a fixed energy.
If your Ga & Tb positions are fixed then I guess -so might work in MSR1a, I
have never tried.
N.B., I meant x-ray or neutron positions, the latter might be better for
the O. In my opinion you should not use peaks in spectra or band gaps as
these are excited state properties, and -eece is ground state. That said,
optimizing the hybrid fraction for positions gave decent gaps for a few
other cases as well. Never published as I have no explanation.
--
Professor Laurence Marks (Laurie)
Northwestern University
www.numis.northwestern.edu
https://scholar.google.com/citations?user=zmHhI9gJ&hl=en
"Research is to see what everybody else has seen, and to think what nobody
else has thought" Albert Szent-Györgyi
On Mon, Feb 12, 2024, 20:09 Pavel Ondračka wrote:
> Dear prof. Marks,
> thanks a lot for your comments, just some follow up (I was not sure
> whether by "you can ask me offline" you meant private email, but
> hopefully this can still be also interesting for the list):
>
> On Mon, 2024-02-12 at 18:56 +0800, Laurence Marks wrote:
> > Many comments/responses:
> > a) You can do both forces and volume optimization with -eece, but not
> > with -so.
>
> Thanks for the clarification, this is very helpful, as I said I was
> under the impression that I can relax O positions with so as long as I
> don't turn on so for O ("UG 5.2.18 init_so_lapw: Since forces are not
> correct for atoms with SO, it can be very useful to suppress SO for
> light atoms (eg. the O-atoms in UO2 ), because then one can optimize
> the O-positions.")
>
> > b) For 4f what you did with case.in0eece is right, but check that it
> > does not get overwritten. I had to edit an overwrite out of my
> > runeece.
>
> Will check, thanks.
>
> > c) Expect the addition of -so to change things quite a lot -- and
> > very little! The nett change in the energy will be very small, and
> > you may want to think about the spin-ordering temperatures. Is your
> > compound ferromagnetic, antiferromagnetic or what?
>
> Honestly I have no idea, right now I have ferromagnetic, but this is
> something I want to take a closer look at as well. It could be quite
> complex, and maybe even questionable if I can even end with some
> results that are relevant for the room temperature optical measurements
> my colleagues are doing while within the limitations of collinear
> model...
>
> > d) People will tell you to use +U which will put the 4f electrons
> > really low. My recommendation is to ignore them. As you noted they
> > are in the valence regime.
>
> Noted
>
> > e) One way to fit the hybrid fraction is to get the best fit
> > (approximately) to the x-ray positions. This turned out for me to be
> > very reasonable.
>
> Just to double check, by "X-ray positions" you mean refined atomic
> positions from XRD or positions of the Tb states in XPS valence band
> spectrum? XPS is something I definitely have on my TODO list.
>
> > f) Beware too large RMTs. If you have these for the metal atoms then
> > you get the tails of the O 2p states within those RMTs and that can
> > give you artifacts.
>
> To be honest I have no feeling here about what are too large RMTs in
> this regard. I have 2.43 for Tb, 1.82 for Ga and 1.65 for O (this is
> almost touching spheres). How big decrease would you recommend 5-10%?
>
> > If you have other questions you can ask me offline if you want. You
> > may want to look at DOI: 10.1103/PhysRevMaterials.2.025001,
> > 10.1016/j.ultramic.2018.12.005, 10.1103/PhysRevMaterials.5.125002,
> > 10.1021/acs.inorgchem.2c04107 Note that the XPS is dominated (cross-
> > sections) by the 4f, and in TbScO3 that are at the Fermi edge (if it
> > is Tb3+, Tb4+ will be simpler).
>
> This is very exhaustive list, thanks. Will definitely read through it.
>
> Best regards
> Pavel
>
> >
> > On Mon, Feb 12, 2024 at 6:15 PM Pavel Ondračka
> > wrote:
> > > Dear Wien2k mailing list,
> > >
> > > I'm trying to calculate a band structure of Tb3Ga5O12 magneto-
> > > optical
> > > crystal (cubic Ia-3d, 80 atoms). While I consider myself quite
> > > experienced Wien2k user, I've always managed to stay away from f
> > > block
> > > elements, so my experience here is none. So besides the few
> > > questions I
> > > have I'll also try to somehow summarize what I did, please correct
> > > me
> > > if something was not OK.
> > >
> > > Luckily I'm not shooting completely blind as I have some high-
> > > quality
> > > optical data where we can see some (very weak but also quite sharp
> > > and
> > > hence noticeable f-f transitions in the band gap so I have some
> > > idea
> > > how the Tb f states at least should look like). Significant optical
> > > absorption start around 4eV but below that I see some very weak
> > > electronic transitions in the 0.2-0.9eV range, around 2.5 and 3.5eV
> > > (reportedly between f states located in the band
Re: [Wien] Few questions about onsite hybrids and so
Dear prof. Marks,
thanks a lot for your comments, just some follow up (I was not sure
whether by "you can ask me offline" you meant private email, but
hopefully this can still be also interesting for the list):
On Mon, 2024-02-12 at 18:56 +0800, Laurence Marks wrote:
> Many comments/responses:
> a) You can do both forces and volume optimization with -eece, but not
> with -so.
Thanks for the clarification, this is very helpful, as I said I was
under the impression that I can relax O positions with so as long as I
don't turn on so for O ("UG 5.2.18 init_so_lapw: Since forces are not
correct for atoms with SO, it can be very useful to suppress SO for
light atoms (eg. the O-atoms in UO2 ), because then one can optimize
the O-positions.")
> b) For 4f what you did with case.in0eece is right, but check that it
> does not get overwritten. I had to edit an overwrite out of my
> runeece.
Will check, thanks.
> c) Expect the addition of -so to change things quite a lot -- and
> very little! The nett change in the energy will be very small, and
> you may want to think about the spin-ordering temperatures. Is your
> compound ferromagnetic, antiferromagnetic or what?
Honestly I have no idea, right now I have ferromagnetic, but this is
something I want to take a closer look at as well. It could be quite
complex, and maybe even questionable if I can even end with some
results that are relevant for the room temperature optical measurements
my colleagues are doing while within the limitations of collinear
model...
> d) People will tell you to use +U which will put the 4f electrons
> really low. My recommendation is to ignore them. As you noted they
> are in the valence regime.
Noted
> e) One way to fit the hybrid fraction is to get the best fit
> (approximately) to the x-ray positions. This turned out for me to be
> very reasonable.
Just to double check, by "X-ray positions" you mean refined atomic
positions from XRD or positions of the Tb states in XPS valence band
spectrum? XPS is something I definitely have on my TODO list.
> f) Beware too large RMTs. If you have these for the metal atoms then
> you get the tails of the O 2p states within those RMTs and that can
> give you artifacts.
To be honest I have no feeling here about what are too large RMTs in
this regard. I have 2.43 for Tb, 1.82 for Ga and 1.65 for O (this is
almost touching spheres). How big decrease would you recommend 5-10%?
> If you have other questions you can ask me offline if you want. You
> may want to look at DOI: 10.1103/PhysRevMaterials.2.025001,
> 10.1016/j.ultramic.2018.12.005, 10.1103/PhysRevMaterials.5.125002,
> 10.1021/acs.inorgchem.2c04107 Note that the XPS is dominated (cross-
> sections) by the 4f, and in TbScO3 that are at the Fermi edge (if it
> is Tb3+, Tb4+ will be simpler).
This is very exhaustive list, thanks. Will definitely read through it.
Best regards
Pavel
>
> On Mon, Feb 12, 2024 at 6:15 PM Pavel Ondračka
> wrote:
> > Dear Wien2k mailing list,
> >
> > I'm trying to calculate a band structure of Tb3Ga5O12 magneto-
> > optical
> > crystal (cubic Ia-3d, 80 atoms). While I consider myself quite
> > experienced Wien2k user, I've always managed to stay away from f
> > block
> > elements, so my experience here is none. So besides the few
> > questions I
> > have I'll also try to somehow summarize what I did, please correct
> > me
> > if something was not OK.
> >
> > Luckily I'm not shooting completely blind as I have some high-
> > quality
> > optical data where we can see some (very weak but also quite sharp
> > and
> > hence noticeable f-f transitions in the band gap so I have some
> > idea
> > how the Tb f states at least should look like). Significant optical
> > absorption start around 4eV but below that I see some very weak
> > electronic transitions in the 0.2-0.9eV range, around 2.5 and 3.5eV
> > (reportedly between f states located in the band gap). So I expect
> > at
> > least three bunches of f states in band gap one occupied and the
> > others
> > unoccupied.
> >
> > I've started with spin-polarized PBE, I'm reasonably sure the
> > structure
> > file is OK, albeit probably not much relaxed (but I was hoping I
> > could
> > find equilibrium volume and do relaxation at a later point). I did
> > not
> > opt for HDLOs even though the Tb sphere is quite big (2.43) since I
> > would also like to try to get few momentum matrix elements later
> > with
> > optics, but I've increased the lmax to 14 and lvnsmax to 8 (lapw2
> > GMAX
> > 16, fft factor 3 and 4x4x4 k-grid).
> >
> > The initial runsp went fine but the band structure is far from OK,
> > I
> > get only a single bunch of f states in the band gap clumped
> > together
> > (some of them are occupied so its metallic), but experimentally I
> > should get and insulator (although the difference between the
> > unoccupied and occupied f states in the band gap is only maybe
> > 0.2eV).
> >
> > Regarding the f electron correction I opted for onsite hybrid and
> > i
Re: [Wien] Few questions about onsite hybrids and so
Many comments/responses: a) You can do both forces and volume optimization with -eece, but not with -so. b) For 4f what you did with case.in0eece is right, but check that it does not get overwritten. I had to edit an overwrite out of my runeece. c) Expect the addition of -so to change things quite a lot -- and very little! The nett change in the energy will be very small, and you may want to think about the spin-ordering temperatures. Is your compound ferromagnetic, antiferromagnetic or what? d) People will tell you to use +U which will put the 4f electrons really low. My recommendation is to ignore them. As you noted they are in the valence regime. e) One way to fit the hybrid fraction is to get the best fit (approximately) to the x-ray positions. This turned out for me to be very reasonable. f) Beware too large RMTs. If you have these for the metal atoms then you get the tails of the O 2p states within those RMTs and that can give you artifacts. If you have other questions you can ask me offline if you want. You may want to look at DOI: 10.1103/PhysRevMaterials.2.025001, 10.1016/j.ultramic.2018.12.005, 10.1103/PhysRevMaterials.5.125002, 10.1021/acs.inorgchem.2c04107 Note that the XPS is dominated (cross-sections) by the 4f, and in TbScO3 that are at the Fermi edge (if it is Tb3+, Tb4+ will be simpler). On Mon, Feb 12, 2024 at 6:15 PM Pavel Ondračka wrote: > Dear Wien2k mailing list, > > I'm trying to calculate a band structure of Tb3Ga5O12 magneto-optical > crystal (cubic Ia-3d, 80 atoms). While I consider myself quite > experienced Wien2k user, I've always managed to stay away from f block > elements, so my experience here is none. So besides the few questions I > have I'll also try to somehow summarize what I did, please correct me > if something was not OK. > > Luckily I'm not shooting completely blind as I have some high-quality > optical data where we can see some (very weak but also quite sharp and > hence noticeable f-f transitions in the band gap so I have some idea > how the Tb f states at least should look like). Significant optical > absorption start around 4eV but below that I see some very weak > electronic transitions in the 0.2-0.9eV range, around 2.5 and 3.5eV > (reportedly between f states located in the band gap). So I expect at > least three bunches of f states in band gap one occupied and the others > unoccupied. > > I've started with spin-polarized PBE, I'm reasonably sure the structure > file is OK, albeit probably not much relaxed (but I was hoping I could > find equilibrium volume and do relaxation at a later point). I did not > opt for HDLOs even though the Tb sphere is quite big (2.43) since I > would also like to try to get few momentum matrix elements later with > optics, but I've increased the lmax to 14 and lvnsmax to 8 (lapw2 GMAX > 16, fft factor 3 and 4x4x4 k-grid). > > The initial runsp went fine but the band structure is far from OK, I > get only a single bunch of f states in the band gap clumped together > (some of them are occupied so its metallic), but experimentally I > should get and insulator (although the difference between the > unoccupied and occupied f states in the band gap is only maybe 0.2eV). > > Regarding the f electron correction I opted for onsite hybrid and > initialized it with init_orb_lapw -eece. > UG says that its better to use LDA for the exchange potential so I > copied case.in0 to case.in0eece_lapw where I replaced "XC_PBE" on the > first line with "EX_PBE VX_LDA EC_PBE VC_PBE". > The onsite hybrid calculation converged fine, I get a nice splitting of > the f states (albeit a bit too much maybe). > The other options would be +U obviously, I went for the hybrid because > it felt more rigorous, but I would also appreciate comments if someone > has maybe better experience with +U? > > Next step was to initialize spin-orbit interaction with init_so_lapw. I > started with the default 001 but I want to also try other directions > later and compare. I opted for no relativistic LOs (no support in > optics) and enabled it only for Tb and Ga. symetso created a new > structure (most notable I have more Tb inequivalent positions) and than > I manually fixed case.inso case.indm and case.inorb as the init_so > script warned me. I also guessed I should fix case.ineece (that seemed > straightforward) but than I thought I should also fix case.in2eece. > Reading UG gives the impression that case.in2eece is normal case.in2 > with extra EECE on the first line and than the optional 3a and 3b > lines. In the case.in2eece created automatically with init_orb_lapw - > eece the 3a and 3b lines looked like: > 1 > 1 1 3 > However reading UG this actually seems wrong? Because UG says (Section > 7.9 page 166) the format for optional 3b is just two values: > jatom rho, l rho > so I wonder if the UG is wrong or if I'm actually applying the hybrid > correction to p instead of f? > > Also, is there anything else I should fix manually after intializing > the so on top of eece
[Wien] Few questions about onsite hybrids and so
Dear Wien2k mailing list, I'm trying to calculate a band structure of Tb3Ga5O12 magneto-optical crystal (cubic Ia-3d, 80 atoms). While I consider myself quite experienced Wien2k user, I've always managed to stay away from f block elements, so my experience here is none. So besides the few questions I have I'll also try to somehow summarize what I did, please correct me if something was not OK. Luckily I'm not shooting completely blind as I have some high-quality optical data where we can see some (very weak but also quite sharp and hence noticeable f-f transitions in the band gap so I have some idea how the Tb f states at least should look like). Significant optical absorption start around 4eV but below that I see some very weak electronic transitions in the 0.2-0.9eV range, around 2.5 and 3.5eV (reportedly between f states located in the band gap). So I expect at least three bunches of f states in band gap one occupied and the others unoccupied. I've started with spin-polarized PBE, I'm reasonably sure the structure file is OK, albeit probably not much relaxed (but I was hoping I could find equilibrium volume and do relaxation at a later point). I did not opt for HDLOs even though the Tb sphere is quite big (2.43) since I would also like to try to get few momentum matrix elements later with optics, but I've increased the lmax to 14 and lvnsmax to 8 (lapw2 GMAX 16, fft factor 3 and 4x4x4 k-grid). The initial runsp went fine but the band structure is far from OK, I get only a single bunch of f states in the band gap clumped together (some of them are occupied so its metallic), but experimentally I should get and insulator (although the difference between the unoccupied and occupied f states in the band gap is only maybe 0.2eV). Regarding the f electron correction I opted for onsite hybrid and initialized it with init_orb_lapw -eece. UG says that its better to use LDA for the exchange potential so I copied case.in0 to case.in0eece_lapw where I replaced "XC_PBE" on the first line with "EX_PBE VX_LDA EC_PBE VC_PBE". The onsite hybrid calculation converged fine, I get a nice splitting of the f states (albeit a bit too much maybe). The other options would be +U obviously, I went for the hybrid because it felt more rigorous, but I would also appreciate comments if someone has maybe better experience with +U? Next step was to initialize spin-orbit interaction with init_so_lapw. I started with the default 001 but I want to also try other directions later and compare. I opted for no relativistic LOs (no support in optics) and enabled it only for Tb and Ga. symetso created a new structure (most notable I have more Tb inequivalent positions) and than I manually fixed case.inso case.indm and case.inorb as the init_so script warned me. I also guessed I should fix case.ineece (that seemed straightforward) but than I thought I should also fix case.in2eece. Reading UG gives the impression that case.in2eece is normal case.in2 with extra EECE on the first line and than the optional 3a and 3b lines. In the case.in2eece created automatically with init_orb_lapw - eece the 3a and 3b lines looked like: 1 1 1 3 However reading UG this actually seems wrong? Because UG says (Section 7.9 page 166) the format for optional 3b is just two values: jatom rho, l rho so I wonder if the UG is wrong or if I'm actually applying the hybrid correction to p instead of f? Also, is there anything else I should fix manually after intializing the so on top of eece? Or should I do it the other way around (first so and then eece)? The reasoning for doing first eece was that I get a metal with plain PBE and an insulator with the onsite hybrid, so I thought it might be easier to converge if I start so from insulator (but I still use TEMP smearing just to be sure I don't end with convergence problems if I get a metal during the convergence as the expected unoccupied occupied f-f distance is very small.) I was also considering mBJ later, just to get some feeling how the conduction bad would shift but I'm not sure if this would work or not on top of eece and so? One last question is regarding the forces. From reading the UG I understood that it should be OK to relax the oxygen positions with onsite hybrid and so (as long as I don't have so or eece enabled for O atoms). Is this correct? So will just switching to MSR1a and running normal runsp -so -eece work or are some other fixes needed? Best regards Pavel ___ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
