# Gaussian syntax error on the input line

I ran a Gold complex in Gaussian 09 with the following exact Route Section PBE0/LANL2DZ Opt Freq NoSymm and it gave me this error message:

QPErr --- A syntax error was detected in the input line.
#T PBE0/LANL2DZ Opt Freq NoSymm


May you kindly please assist me.

This was the input file:

#T PBE0/LANL2DZ Opt Freq NoSymm

au1i2se2pc4h10o2

0 1
Au 1.360814 1.469089 4.400746
C 5.307642 1.389607 6.843985
H 5.507275 1.229404 5.910229
H 4.870358 2.257890 6.915128
C 6.510720 1.389607 7.612332
H 7.089684 2.096802 7.304637
H 6.959811 0.547877 7.509174
H 6.306354 1.532993 8.538974
C 1.456104 -1.956071 7.162351
H 0.690196 -1.468381 7.503839
H 1.363535 -2.024224 6.198359
C 1.488953 -3.274870 7.738612
H 0.666753 -3.731582 7.532296
H 1.584937 -3.205832 8.690153
H 2.226021 -3.766101 7.374002
I 1.201101 1.134698 1.820913
I -0.420347 3.370638 4.490387
O 4.402687 0.338108 7.352659
O 2.673550 -1.232944 7.482496
P 3.034067 0.042485 6.682134
Se 3.109165 -0.249598 4.533606
Se 1.591287 1.649826 6.831890

• I think that PBE0 is defined in Gaussian as PBE1PBE. What is the 'T' at the start of the input line included for? – LigninPauling Mar 20 '19 at 12:10
• And if anything, it would be pbeZERO and not pbeOH - that is, a number, not a letter – TAR86 Mar 20 '19 at 15:18
• @LigninPauling The formatting was bad, because not as code, so it ate the route sign. The #T produces terse output (if you didn't know already), and you are right, definition wise. Related: PBE vs. PBEPBE functional Btw: I highly recommend not doing compound jobs. – Martin - マーチン Mar 20 '19 at 17:10
• @Martin-マーチン That makes more sense now. I've noticed before you recommending not to do compound jobs. I'm curious as to why this is? – LigninPauling Mar 20 '19 at 18:36
• @LigninPauling there are three principle issues: 1. If you specify nonstandard keywords, they will not be copied to the second part. That might be an issue. 2. Creating a fallback, if anything after the optimisation fails. 3. Some visualisation tools can't really cope with them (molden). 4. You don't have to, but that's just a question of taste. It's easier to locate errors though. By far most important is the first. But if you know what you're doing, and know what you're expecting, you'll be fine either way... – Martin - マーチン Mar 20 '19 at 19:06

Bryan, I am probably late, but here is a couple of suggestions: The error that you get most likely comes from the wrong keyword: in Gaussian, the PBE0 method is defined using the keyword PBE1PBE. Change it, and it will be solved.

As for the "Opt Freq" keywords, it is not a good computational routine. You should run an optimization job first, and then a frequency calculation. What I would do if you don't want to run two separate jobs, is the following. After the geometry, leave a blank line. Then, on the following line, type:

On the next line, the new job specification. Don't forget to use the same chk, and the keywords Geom=Check Guess=Read in the input route.

In this way, Gaussian starts again, and you can always save these two jobs in two separate files. I hope this helps, feel free to ask more questions!

• Thank you so much Pier. The calculation ran successfully with PBE1PBE. – Bryan Apr 1 '19 at 9:54