Issue with modification of CHOOSE keylist

Issue with modification of CHOOSE keylist

Postby kerridge » Tue Dec 04, 2018 5:28 am

Hi,

I'm trying to modify the $CHOOSE keylist for a uranium complex. The keylist as produced from a default NBO run is given below:

$CHOOSE
LONE 1 1 2 1 26 1 50 3 51 3 52 3 53 3 54 3 55 3 56 3 57 3 58 1 73 3 75 3
77 3 79 3 END
BOND S 2 3 D 2 9 D 3 4 S 3 18 S 4 5 S 4 6 D 6 7 S 6 90 S 7 8 S 7 9 S 9 10
D 10 11 S 10 17 S 11 12 S 11 50 S 12 13 D 12 14 S 14 15 S 14 91 S 15 16
D 15 17 S 17 51 S 18 19 D 18 25 D 19 20 S 19 52 S 20 21 S 20 22 D 22 23
S 22 86 S 23 24 S 23 25 S 25 53 D 26 27 S 26 33 S 27 28 S 27 42 S 28 29
D 28 30 S 30 31 S 30 87 S 31 32 D 31 33 S 33 34 D 34 35 S 34 41 S 35 36
S 35 54 S 36 37 D 36 38 S 38 39 S 38 89 S 39 40 D 39 41 S 41 55 D 42 43
S 42 49 S 43 44 S 43 56 S 44 45 D 44 46 S 46 47 S 46 88 S 47 48 D 47 49
S 49 57 D 58 59 S 58 60 S 59 61 S 59 62 D 60 63 S 60 64 S 61 65 D 61 66
S 62 67 D 62 68 S 63 66 S 63 69 D 64 70 S 64 71 S 66 93 D 67 72 S 67 73
S 68 74 S 68 75 S 70 76 S 70 77 D 71 78 S 71 79 S 72 80 S 72 81 D 74 81
S 74 82 S 76 83 D 76 84 S 78 84 S 78 85 S 81 92 S 84 94 END
$END

However, we expect to find three U-C bonding interactions. Visualisation of the NBOs does indeed reveal three orbitals that appear to show U-C interactions. The U centre is centre 1 and the coordinating C centres are 2, 26, and 58. The default NBO analysis reports above that each of these centres has a lone pair. Modifying the $CHOOSE keylist to

$CHOOSE
LONE 1 1 50 3 51 3 52 3 53 3 54 3 55 3 56 3 57 3 73 3 75 3
77 3 79 3 END
BOND S 1 2 S 1 26 S 1 58
S 2 3 D 2 9 D 3 4 S 3 18 S 4 5 S 4 6 D 6 7 S 6 90 S 7 8 S 7 9 S 9 10
D 10 11 S 10 17 S 11 12 S 11 50 S 12 13 D 12 14 S 14 15 S 14 91 S 15 16
D 15 17 S 17 51 S 18 19 D 18 25 D 19 20 S 19 52 S 20 21 S 20 22 D 22 23
S 22 86 S 23 24 S 23 25 S 25 53 D 26 27 S 26 33 S 27 28 S 27 42 S 28 29
D 28 30 S 30 31 S 30 87 S 31 32 D 31 33 S 33 34 D 34 35 S 34 41 S 35 36
S 35 54 S 36 37 D 36 38 S 38 39 S 38 89 S 39 40 D 39 41 S 41 55 D 42 43
S 42 49 S 43 44 S 43 56 S 44 45 D 44 46 S 46 47 S 46 88 S 47 48 D 47 49
S 49 57 D 58 59 S 58 60 S 59 61 S 59 62 D 60 63 S 60 64 S 61 65 D 61 66
S 62 67 D 62 68 S 63 66 S 63 69 D 64 70 S 64 71 S 66 93 D 67 72 S 67 73
S 68 74 S 68 75 S 70 76 S 70 77 D 71 78 S 71 79 S 72 80 S 72 81 D 74 81
S 74 82 S 76 83 D 76 84 S 78 84 S 78 85 S 81 92 S 84 94 END
$END

i.e. defining three single U-C bonds instead of the three C lone pairs results in the error:

>NATURAL BOND ORBITAL ANALYSIS:
>Parsing the $CHOOSE keylist
>
>Linear dependence encountered; $CHOOSE structure is likely bogus at atom 1

Could anyone help with this?

Thanks,

Andy
kerridge
 
Posts: 1
Joined: Fri Nov 30, 2018 9:03 am

Re: Issue with modification of CHOOSE keylist

Postby ericg » Mon Jan 21, 2019 2:57 pm

Andy,

The modification that you've made to the $CHOOSE keylist is fine, replacing three carbon lone pairs with three U-C single bonds. The "linear dependence" failure arises when the NBO search algorithm is unable to identify three orthogonal U-C bonds. By default, a two-center NBO must have at least 5% character from each atom. Thus, if the carbon lone pairs aren't at least 5% delocalized on to U, the search will reject the proposed U-C bond and fail.

You might instead use $CHOOSE to request only one or two U-C bonds, rather than all three. Can the search identify at least one U-C bond?

Eric
ericg
 
Posts: 317
Joined: Sat Dec 29, 2012 9:31 am


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