Periodic Boundary Conditions in Gaussian
- From: freddie salsbury <salsbufr)at(wfu.edu>
- Organization: Wake Forest University
- Subject: Periodic Boundary Conditions in Gaussian
- Date: Wed, 26 Nov 2003 13:19:31 -0500
hello --
We're trying to learn how to use the PBC routines in Gaussian 03, and
we
are reaching a stumbling block with our test case of diamond. If
anyone has had much success with PBC in gaussian03 we would appreciate
your advice.
Our input file, a test case of diamond, with a tiny basis set. (Before
we do any real calcs we'd like to understand the simple case.)
-------------------------------
%chk=diamond2G.chk
%mem=1024MB
#HF/STO-3G PBC(NKPoint=48,CellRange=20) Pop(Full)
diamond test
0 1
C 0.445875 0.445875 0.445875
C -0.445875 -0.445875 -0.445875
TV 1.7835 1.7835 0.0000
TV 1.7835 0.0000 1.7835
TV 0.0000 1.7835 1.7835
----------------------------------
First, the gaussian output says it turns symmetry off (even if you
turn
it on, it cannot identify any symmetry).
We varied the CellRange from 20 to 50 and obtained the following results:
NClRep
CellRange Energy Time (min) MaxNCR NMtPBC Convg
10 -74.8774038316 8.01 285 285 0.3482D-04
15 -74.8788470298 7.40 591 591 0.3388D-04
20 -79.7834971028 335.50 1357 1357 0.1513D-02
25 -77.9532971257 47.78 1717 2179 0.1892D-05
30 -78.4667709573 26.46 1721 3185 0.1067D-04
35 -78.8229423341 32.52 1721 4501 0.7331D-05
40 -78.9686326165 43.85 1721 6775 0.2602D-05
45 -86.8332484908 1479.41 1721 8903 0.2117D-03
50 -83.4676895141 1724.68 1721 11387(convergence failure)
(the Cellrange=50 ended with an abnormal termination due to failure to
converge)
The ones that took a long time to run (20 and 45) not only had large
Convg values in the SCF, but also in the population analysis had
inequivalent carbons.
I'd assume that the energy oscillations are due to the tiny basis set;
my chief concerns are with the convergence behavior and understanding
the methods.
My questions are, and I'd appreciate any assistance with these,:
1) Can one enforce symmetry (space group) in gaussian with PBC? If so, how?
2) What are MaxNCR, NClRep, and NMtPBC ?
3) Why are these parameters be the same for Cellranges <=20, but
afterwards the first two level off, while NMtPBC increases between
quadratic and cubic
4) Why would the convergence behavior be so erratic? i.e,. some cell
ranges seem okay, but some take considerably longer in a seemingly
random fashion, with odd results.
5) Does anyone know of any publications or white papers discussing the
implementation of PBC in gaussian03? There seems to be virtually no
documentation, or citations, in the G03 manual.
6) any suggestions on how to run PBC calcs in G03?
thanks for any help you can provide!
cheers
Fred
Dr. Freddie Salsbury, Jr.
Assistant Professor
Department of Physics
Wake Forest University
Winston Salem, NC 27109
http://www.wfu.edu/~salsbufr
http://csb.wfu.edu/(Center for
Structural Biology)