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I need some help regarding running Gaussian 03. I have a complex molecule (64 atoms with 6 types of atom)...and finished geometry optimization successfully using method b3lyp with basis set pVDZ.. it took 4 days to complete this optimization procedure...Now i want to do frequency calculation with the same method and basis set...For this freq. calculation will it take the same time as it took for geometry optimization..more? or less? or the same?..When i did my geom. opt. after 1 days it got aborted due to lack memory...so i took the last value (i.e., coordinates values) from the aborted file and then repeated..so like this i did 4 times and finally everything converged successfully...Now if i do this freq. calculation using the converged values...if it get aborted...what should i use from the aborted file and repeat it???

Also for another molecule i successfully made a freq. calculation...but now i dont know how to interpretate it..i just want to know how to plot Raman and IR spectrum...which values in X and X should i take for plotting from the result output file????is there any thing to tell about Normal mode analysis from this output file???or how to assign certain modes to certain vibrations peaks??

Thanks for ur reply...

Rajini

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# Normal Mode Analysis+IR/Raman

Can you offer guidance or do you also need help?

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