Formerly known as the InitialConditionsSolver module of GRChombo (ascl:2306.039), the multigrid solver GRTresna solves the constraint equations for the initial data required in numerical relativity simulations. In particular, it focuses on scenarios with fundamental fields around black holes and inhomogeneous cosmological spacetimes. GRTresna makes use of the Chombo library (ascl:1202.008) for adaptive mesh refinement to allow automatic increasing of the grid resolution in regions of arbitrary shape and topology.

GRFolres performs simulations in modified theories of gravity. It is based on GRChombo (ascl:2306.039) and inherits all of the capabilities of the main GRChombo code, which makes use of the Chombo library (ascl:1202.008) for adaptive mesh refinement. The code implements the 4∂ST theory of modified gravity and the cubic Horndeski theory in (3+1)-dimensional numerical relativity. GRFolres can be used for stable gauge evolution, solving the modified energy and momentum constraints for initial conditions, and monitoring the constraint violation and calculating the energy densities associated with the different scalar terms in the action. It can also extract data for the tensor and scalar gravitational waveforms.