Is SOC calculation running in parallel or serial?


I would like to run a TDDFT -SOC calculation using Qchem 5.2. However, I would like to know how is run the part dedicated to SOC.
I have the feeling that this runs with only one node and that causes some problem with the cluster management… if it is truly the case is it possible to compute the SCF convergences cycles, the excitation energies and so on in parallel, stop the calculation to compute SOC in serial and restart the calculation in parallel ?

Thank you for your attention,


Most of Q-Chem, where parallel, utilizes single-node parallelism using OpenMP. If you want to run across multiple nodes, MPI was present in 5.2 and is no longer supported in 6.0. The SOC calculation was likely never MPI parallel, but may be OpenMP parallel. Have you tried using -nt as in 2.2.1 General Usage‣ 2.2 Running Q-Chem ‣ Chapter 2 Installation, Customization, and Execution ‣ Q-Chem 6.0 User’s Manual?