Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: anastasiya119 on October 28, 2016, 05:03:08 AM
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Hello! Could anybody give me any instructions about optimization of H3O & H2O system in Gaussian? I`m not a chemist, that`s why I need your help.
I need to obtain energy of activation for proton transfer from hydronium to water molecule, so, I suppose coordinates of two oxygens to be frozen, because then this algorithm of calculation will be used for the structures, which coordinates should be taken from PDB files.
As I see, firstly I should do geometry optimization for reactants and products before PES and searching a transition state. While I try to optimize reactants, I start from this:
(https://pp.vk.me/c637321/v637321642/14fb2/45DVi-je0Rk.jpg)
I use B3LYP/6-31g(d), and the input code is:
# B3LYP/6-31g(d) Opt
Optimization of H3O H2O
1 1
O -1 0.0000000 0.0000000 0.0000000
H 0 0.9700000 0.0000000 0.0000000
H 0 -0.3921668 -0.8871895 0.0000000
H 0 -0.3954392 0.6020616 0.6496535
O -1 2.5440439 0.0000000 0.0000000
H 0 3.5040439 0.0000000 0.0000000
H 0 2.2971964 0.9277210 0.0000000
After optimization I get "Error termination request processed by link 9999" in the end of the output file, and picture is:
(https://pp.vk.me/c637321/v637321642/14fab/hvqrE5E-hzk.jpg)
Does anybody know how to put it right and how should I optimize such system?