Hello,
I am trying to study the effect of distance between molecules to the Raman spectra. For example, I want to fix the distance between carbonyl oxygen of benzoic acid to one H of water to see the effect of hydrogen bond distance. I tried doing it but the distance always go to 1.9A after optimization. Does anyone know how to do it?
Thanks in advance!
Hello Marvin,
I just want to include a small comment regarding freezing of bond in Gaussian09. To best of my knowledge in G09 rev C.01 (and above) the modredundant format e.g,
B 1 2 1.5 F doesn't work any more. In newer version of Gaussian it'll ignore the specified frozen length value (1.5) and do a full optimization instead. In older version this input will work fine but not in newer ones. Maybe that is what is happening in your optimization.
In newer version of G09, you first change the respective bond length to the value you want to be frozen at (e.g 1.5 Ang) by Gaussview and then include
B 1 2 F at the end of the file along with opt=modredundant. This will keep the bond length frozen at 1.5 Ang during optimization.
More detail can be found at: http://mgcf.cchem.berkeley.edu/mgcf/faqs/modredundant.html
Dear Marvin,
# hf/3-21g Opt=ModRedun freq
C7H8O3
0 1
6 -2.529904000 1.165574000 0.012721000
6 -1.149963000 1.210855000 0.001700000
6 -0.422793000 0.032434000 -0.005707000
6 -1.066385000 -1.193148000 -0.002902000
6 -2.447798000 -1.237384000 0.007926000
6 -3.177401000 -0.059767000 0.016070000
1 -3.097608000 2.074153000 0.018148000
1 -0.622642000 2.142397000 -0.002012000
1 -0.482278000 -2.088501000 -0.010387000
1 -2.953319000 -2.182045000 0.009675000
1 -4.248869000 -0.096631000 0.024276000
6 1.048209000 0.120109000 -0.017232000
8 1.661097000 1.178257000 -0.021989000
8 1.662841000 -1.059932000 -0.020968000
1 2.654193000 -0.960979000 -0.036127000
8 4.047265000 -0.093458000 -0.039477000
1 4.701763000 -0.066804000 0.668262000
1 3.555344000 0.747437000 -0.087815000
13 18 1.8 F
in where 13 and 18 the two atoms in two molecules you want to fixed .
The distance 1.8 you can change it as you like
Hello Marvin,
I just want to include a small comment regarding freezing of bond in Gaussian09. To best of my knowledge in G09 rev C.01 (and above) the modredundant format e.g,
B 1 2 1.5 F doesn't work any more. In newer version of Gaussian it'll ignore the specified frozen length value (1.5) and do a full optimization instead. In older version this input will work fine but not in newer ones. Maybe that is what is happening in your optimization.
In newer version of G09, you first change the respective bond length to the value you want to be frozen at (e.g 1.5 Ang) by Gaussview and then include
B 1 2 F at the end of the file along with opt=modredundant. This will keep the bond length frozen at 1.5 Ang during optimization.
More detail can be found at: http://mgcf.cchem.berkeley.edu/mgcf/faqs/modredundant.html
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