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.
--
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/
--------------------------------------------------------------------------
-------------- next part --------------
A non-text attachment was scrubbed...
Name: brj.f
Type: text/x-fortran
Size: 3680 bytes
Desc: not available
URL:
<http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20101015/f8063dbe/attachment.f>
