I am trying to run a scan where I have two dummy atoms (or sometimes a carbon atom) and then move a lithium atom in small steps between the two. The problem I have come across is that I am not allowed to set an angle of 0 degrees. The error reads:
"Error on Z-matrix line number 62: angle Alpha is outside the valid range of 0 to 180."
but line 62 reads (inserted table headings above):
CD Cent Atom N1 Length/X N2 Alpha/Y N3 Beta/Z J
62 61 Li 61 2.280000( 61) 1 0.000( 121) 2 0.000( 180) 0
Where the angle is 0.000. I'm assuming this means I can't do an angle of 0 degrees putting the Li on a straight line between the two atoms. So how else can I go about running this same scan, moving a Li atom along a straight line between two other atoms?
Dear Adam Chopdat
Hoping that you are fine.
With respect to your question, I could suggest you next:
Angle of 0° means that all are in the same place and for this reason it could be not allowed for the calculation in Gaussian. Are you sure that you are indicating the correct angles deviation? I suggest you that do not indicate 0° between scan step if no as I suggest you in the second figure of the attached file (I don't know if indicate 0° in the scan have a signification in chemistry/physics since the distortion of p orbital of carbon with respect to S orbital of Li).
If you have any doubt, I could run the calculation and compare the results,
With kind regards,
Julián Sánchez.
Dear Julián,
Thank you for your help, I appreciate it. I have attached a file to help explain a bit better. The angle alpha is defined in my file between the Li-C-C, as the distance which is being scanned is defined by X. So the distance from the first carbon will change, with the vector being directly towards the other carbon. This is why I defined the angle as being 0. If you could advise on how I can otherwise carry out this scan I would appreciate it.
I could attach my file but it is a large calculation, requiring more than one day to run on a cluster computer.
Regards,
Adam
This calculation shouldn't be much of a problem with a properly set up Z-matrix. You essentially want to make sure that the definition of the positions of these three atoms are not all depending on each other.
If you don't want to post the result of your calculation, you could at least post the input file, so that we can see how you set it up.
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