Hello Miguel,

If you want to use the zero-point energy you must run a frequency job at same level of calculus. In this case, from the result obtained in DFT single point, you can do it. Practically at final of the output you will find all thermodynamic results, with Ezpe, enthalpy, etc...

I hope it helps you,

Joaquim Rius

Hello Joaquim,

I checked from the single point output file and nothing related to the thermodynamic results appears, I also run the frequency calculation but this error occur:

LenV= 6739158 MaxCom= -201

Do you know how to solee it?

I've never had this error. Maybe could come from the opt structure. In fact, the method in the optimized structure and frequency are different. Which kind of Oniom did you use? QM/MM or QM/QM ? How many atom has the molecule?

The system has 442 atoms, I'm using QM/MM

the keyword is:

for the optimization in ONIOM: # opt freq=noraman oniom(b3lyp/6-31g(d,p):uff)

for the single point calculations when all the system, all the atoms are in DFT layer:

 # b3lyp/6-31g(d,p)

So for the sp calculation output there are no thermodynamic results

Hello Miguel,

I have made calculus to test opt+freq with onion MQ/MM successfully.  I made that because I think that the calculation of frequency with the oniom optimized structure won't be representative. Structure optimization and frequency should be at same level. For this reason I suggest you to run the freq job with ONIOM. Even so, I am not specialized with Oniom and I don't know if the simplifications can imply  theoretical problems. Also I think is a good start to investigate freq calculation with Oniom and its problems.

I have attached the results of my test. The results are practically at final in output. For fast search use the word " Thermochemistry " in document.

I hope it helps you,

Joaquim Rius

Excellent I will see your results and I'll continue to search. Once I have succesfully results I'll tell you.

Thanks a lot.

As Joaquim suggested, you shoud do frequency calculations.

"LenV= 6739158 MaxCom= -201" means that you run out of disk space and/or memory to run this job. Frequency calculations require a lot of memory (I mean A LOT).