[Wien] mbj on Diamond

[Peter Blaha]

I don't quite understand where the seg.faults come from mentioned recently.

Anyway, the modified routine I sent out a few days ago is using a wrong
bound for tau and thus leads to (slightly) incorrect results for most cases.

Please use and test the attached one.

Peter Blaha

Am 15.10.2010 13:38, schrieb Peter Blaha:
> Hi,
> After I got the struct file, I could verify the problem.
>
> As expected, it is again in the SRC_lapw0/brj.f subroutine,
> where one has to find the root of a function.
>
> For strange densities this is numerically non-trivial.
>
> The problem at the nucleus of heavy elements was solved before, but
> here is the problem in the interstitial, when rho is very small and
> also grad-rho, tau and laplace-rho are sufficiently small.
>
> Then the required functions are "nearly" zero (lt. 10^-6) for a range
> of x=10-30; but using x=30 produces a V-xc potential of -100 Ry,
> which is the reason for your "Eigenvalues below zero".
>
> When such problems occur again, please check also case.output0.
> The Fourier coefficients of Vxc must "converge", i.e. (0 0 0) should be
> order one, while (0 0 30) should be order 10^-5 .
>
> The attached subroutine brj.f should fix these problems (at least your case converges
> smoothly).
>
> Dear All,
>
>
>
> We are performing the mbj calculations for a carbon based compound. According to the usersguide there are three SCF cycles for mbj calculations: first a regular calculations
> within LDA/GGA (we use the PBE-GGA here), second one more cycle run_lapw –NI –i 1 , and third the mbj run after changing the potential energy functional indxc=28 in case.in0 and
> index=50 in case.in0_grr.
>
> Here we call the regular SCF cycles C1.scf, second one-more SCF cycle as C2.scf, and the third the mbj as cycle C3.scf.
>
> The first regular cycle and the second run_lapw –NI –i 1 are converged smoothly. However, the third mbj cycle is stopped at lapw2 in its second iteration.
>
> We analyzed the problem to find the source of the error. The result is given below, where the C2.scf line refers to the last :ITE of the second one more SCF cycle, and the C3.scf
> refers to the first :ITE of the third mbj run:
>
>
>
> C2.scf::NTO033: TOTAL CHARGE IN SPHERE 1 = 3.9781366
>
> C3.scf::NTO033: TOTAL CHARGE IN SPHERE 1 = 2.4250427
>
>
>
> C2.scf::CTO033: TOTAL CHARGE IN SPHERE 1 = 3.9781254
>
> C3.scf::CTO033: TOTAL CHARGE IN SPHERE 1 = 3.9470631
>
>
>
> C2.scf::DIS : CHARGE DISTANCE ( 0.0000355 for atom 33 spin 1) 0.0000136
>
> C3.scf::DIS : CHARGE DISTANCE ( 1.8978668 for atom 25 spin 1) 1.5016586
>
>
>
> C2.scf::NEC01: NUCLEAR AND ELECTRONIC CHARGE 366.00000 365.98257 1.00005
>
> C3.scf::NEC01: NUCLEAR AND ELECTRONIC CHARGE 366.00000 365.98171 1.00005
>
>
>
> C2.scf::FER : F E R M I - ENERGY(TETRAH.M.)= 0.21390
>
> C3.scf::FER : F E R M I - ENERGY(TETRAH.M.)= -1.44751
>
>
>
> The result clearly shows that there is a jump in :NTO, :DIS, and :FER (But in :CTO) after changing the functional to index=28.
>
>
>
>
>
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-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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