Hi,
I am trying to run some QM/MM calculations with Sander.quick.cuda, but the energy minimization of the QM region is being troublesome.
I did a MM minimization of the lipids and solvent molecules of my system (restraining protein atoms and Cu ion) due to lipids always having very bad clashes.
The next minimization is already with QM/MM. I have used multiple basis set with HF, B3LYP and O3LYP and the results are as follows:
Regardless of HF or the other DFT methods I have used, QM energy explodes when using GPUs and higher accuracy basis sets suchs as 6-31G(d), cc-pVDZ, def2-SVPD. But if I use lower accuracy methods such as 6-31G or 3-21G, it can run on GPUs and energies look fine (QM atoms don't seem to be manipulated during the minimization only MM atoms).
Using CPUs, I can run with the more accurate basis sets, but it is slow, and the QM atoms also don't seem to be manipulated during the minimization. So, when I use the restart file to continue next step with GPUs (maybe heating or another minimization), the energies explode again despite using the same method and basis set that had been used in the minimization with CPUs.
Can you point at what I am doing wrong or what should I check? This is my first QM/MM simulation, so I don't know what I am doing.
Thanks for your invaluable help and time.
Fernando
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Received on Tue Mar 05 2024 - 12:00:02 PST
