Hello,

The keyword "nelec" is missing from the manual for Gaussian16.

You can download the correct LANL08(d) basis set from the "Basis Set Exchange".

Best regards.

Try this (my comments start with ! but should be deleted):

-1,1

GEOMETRY

!

H C O 0 ! the last entry is a zero

aug-ccpvtz ! no hyphen after cc

**** ! No blank line after **** here.

I 0 S 1 1.00 0.7242000 1.0000000 S 1 1.00 0.4653000 1.0000000 S 1 1.00 0.1336000 1.0000000 P 1 1.00 1.2900000 1.0000000 P 1 1.00 0.3180000 1.0000000 P 1 1.00 0.1053000 1.0000000 P 1 1.00 0.0308 1.0 D 1 1.00 0.2940 1.0 **** ! One blank line after **** here. I 0 I-ECP 3 46 f potential 5 0 1.0715702 -0.0747621 1 44.1936028 -30.0811224 2 12.9367609 -75.3722721 2 3.1956412 -22.0563758 2 0.8589806 -1.6979585 s-f potential 5 0 127.9202670 2.9380036 1 78.6211465 41.2471267 2 36.5146237 287.8680095 2 9.9065681 114.3758506 2 1.9420086 37.6547714 p-f potential 5 0 13.0035304 2.2222630 1 76.0331404 39.4090831 2 24.1961684 177.4075002 2 6.4053433 77.9889462 2 1.5851786 25.7547641 d-f potential 5 0 40.4278108 7.0524360 1 28.9084375 33.3041635 2 15.6268936 186.9453875 2 4.1442856 71.9688361 2 0.9377235 9.3630657 ! At least one blank line after this.