Hello everyone!

I am trying to obtain simple geometry optimization of a single DNA-PNA mononucleotide having around 80 atoms using Gaussian16

This is the main input line I am using.

#n PW91PW91/6-31++G** Opt freq EmpiricalDispersion=GD3 S8=1.0 scrf(pcm,solvent=water)

Below is the error I am getting,

QPErr --- A syntax error was detected in the input line.

t freq EmpiricalDispersion=GD3 S8=1.0 scrf(pcm,solvent=water)

I can understand that this is a syntax error focusing on the S8 letter. But I am not been able to find its solution, Please help

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