Subject: Periodic Boundary Conditions in Gaussian

From: freddie salsbury <salsbufr.-at-.wfu.edu>
Date: Wed, 31 Dec 2003 13:12:12 -0500

Dear CCler's --

About 1 month ago, I asked if anyone has had much success in G03 with 
PBC, because we seem unable to run a routine calc with diamond in 3D. 
Since they we have discovered that 1 or 2D calculations work fine, its 
just in 3D that things seem to break down.

Has anyone succesfully ran a 3D calc with the PBC code in gaussian and 
with HF? If so would you share with us the input file? The one we've 
been using is attached below, along with our results.

thanks for any assistance,

cheers
Fred

-------------------------------
%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.

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)