# CCL:G: The l502 error in CBS-QB3 calculation

*From*: "dewdew zhou" <dewdew(-)126.com>
*Subject*: CCL:G: The l502 error in CBS-QB3 calculation
*Date*: Mon, 2 Nov 2009 13:58:17 -0500

Sent to CCL by: "dewdew zhou" [dewdew|,|126.com]
Dear all,
I have used the B3lyp/cbsb7 method to calculate the geometry of a very loose
complex, and it is termined well. Based on this geometry i used the CBS/QB3
method to calculate the single point energy, and it always shows the following
error:
>>>>>>>>>> Convergence criterion not met.
SCF Done: E(UHF) = -267.358083472 A.U. after 129 cycles
Convg = 0.4652D-04 -V/T = 2.0021
<Sx>= 0.0000 <Sy>= 0.0000 <Sz>= 0.5000 <S**2>= 0.7554
S= 0.5027
<L.S>= 0.000000000000E+00
Annihilation of the first spin contaminant:
S**2 before annihilation 0.7554, after 0.7500
Convergence failure -- run terminated.
Error termination via Lnk1e in /ichec/packages/gaussian/09a02/l502.exe at Tue
Oct 20 10:27:32 2009.
Job cpu time: 0 days 0 hours 1 minutes 49.3 seconds.
File lengths (MBytes): RWF= 48 Int= 0 D2E= 0 Chk= 3 Scr=
1
Do you know how to fix it?
If you know, please tell me, i will very appreciate that. Thanks a lot!