Does any one know how to add new solvents other than those listed in gaussian 03 for PCM solvation study. pls. write how to write it's command in route sec. ?
my method is freq+opti
method : RHF
and solvation i want SCRF=PCM
now how to add new solvent ? and which parameter i have to feed and how pls. write it's example. for PCM, Onsager and other methods
Hi,
You need to write scrf(pcm, read) in the route section
Then after the coordinates and the basis set specification you need to add radii=uff
Eps=7.2 (Here EPS is the dielectric constant of your chosen solvent, I have taken tetraglyme whose EPS is 7.2). This will create a solvation sphere of water (which is the default case) with the given EPS
Thank you...
I have added all these four parameter eps, rsolv, refractive index, and molar volume, but i want to know that is this calculation consider solvent molecules coordinates like x y and z?
Once again thank you for your precious attention...
No it creates a polar continuum model without using explicit solvent molecules. It doesn't consider the coordinates. In order to see the role of explicit solvent molecules, you have to create a model with say 8 or 10 solvent molecules around your substrate and let it optimize. Then only you can figure out the effect of solvent molecules.
Thank you so much, i was also thinking about this idea but unfortunately at that time i was not sure that this will work or not but now you are telling this so i will definitely try it. and one more thing is that if we add more solvent molecules around our main component. are i have to change basis function set in this case ? and do you have any idea for selecting best function set and its BSSE.
One more thing i was beginner in this study, but now i am sure that i will be perfect in this calculation with your help. one more thing that non was help me like this except you.
Thank you....
I am sorry if i disturbing you...
No you don't have to change your chosen basis set and do it at the same of level of theory as your earlier computations. Try with 6-31++G(d,p) basis set. This is a relatively small double-zeta basis with diffuse function on all atoms. There is nothing as the best basis set to avoid BSSE. If you are dealing with so many fragments you need to compute the basis set superposition error using the counterpoise correction. Another thing is that you must consider not only the energy but the free energy also since there would be significant entropic effect during clustering of the isolated solvent molecules.
Thank you..
i want to learn more about basis set selection. i am a beginner in all these calculation whatever i learned till now, all is from reading from various sources. so do you have any text material of reference from it i can learn how to make a proper basis set or select basis set. If you have please inform me i will download or purchase it from market. and from your reply, you are looking a expert in all these gaussian related calculation. from where you learn all these thing means course or degree ?
I also want to expert like you....
because i want to add all these calculation in my research area of transport properties and thermophysical properties.
Thank you...
I suppose you could check the dielectric constant of solvent , and add it, or check and compare with current ones in default of software.
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