The ABINIT Users Mailing List ( CLOSED )

[Hua Bao <hbao@purdue.edu>]

Dear all,

First, I have a general question. How to get a faster SCF  
calculation? I appreciate if you can point out which literatures to  
refer.

I am doing a geometry optimization of TiO2 cluster contains less than  
40 atoms. The SCF calculation is really slow. It take a few hundreds  
steps to get convergent. The energy sometimes is fluctuating. So I  
expect it would take a really long time to achieve geometry  
optimization. Parallel running does not help too much, either. Since  
my initial geometry is a little far from optimization. Is there any  
faster way to get a optimized structure?

Here is my input file, NCpp is used.

ionmov  3              # Use the modified Broyden algorithm
ntime   1000             # Maximum number of Broyden "timesteps"
tolmxf  1.0d-4         # Stopping criterion for the geometry  
optimization : when
iscf    5
chkprim 1

toldff  1.0d-4         # Will stop the SCF cycle when, twice in a row,
                       # the difference between two consecutive  
evaluations of
                       # forces differ by less than toldff (in  
Hartree/Bohr)


xangst   9.186000    9.186000   11.779326
.......
acell  15 15 15  angstrom  # The keyword "acell" refers to the
angdeg 90 90 90

ntypat 2          #
znucl 22 8      # The keyword "znucl" refers to the atomic number of the


#Definition of the atoms
natom 33
typat 1 2 2 1 2 1 2 2 2 1 2 2 2 1 2 2 1 2 2 2 1 2 1 2 2 1 2 1 2 1 2 2 2

#Definition of the planewave basis set
ecut 30.0         # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
nkpt 1
#Definition of the SCF procedure
nstep 500          # Maximal number of SCF cycles


Thanks,

Hua Bao
Graduate Student
School of Mechanical Engineering,
Purdue University
O: 765-494-6944