I want to perform molecular dynamics simulations of a system with toluene solvent represented by TraPPE-UA (7-site) model using GROMACS-5.1.4. It is a rigid model and therefore has no intramolecular interactions. In the [ constraints ] directive of the itp file for toluene (attached here), along with 1-2 (and 2-3) distance constraints that rigidify bonds, I specify 1-3 distance constraints to rigidify 1-2-3 angle. If my understanding of the GROMACS manual is correct, such 1-3 constraints are called coupled-angle constraints and LINCS algorithm should not be used with them. SHAKE algorithm cannot be used with domain decomposition. Please suggest if there is a way to run parallel simulations using SHAKE algorithm. If it is not possible, please suggest a method to fix all the bonds and angles in a toluene molecule without using SHAKE.

Thank you all in advance.