MRCC
MRCC is a high-accuracy quantum chemistry program suite for ab initio and density-functional electronic structure calculations, developed at TU Budapest. Its core strength is an automated tensor-programming framework that enables general, index-independent implementations of advanced methods. MRCC supports highly sophisticated models, including arbitrary single- and multi-reference coupled-cluster (CC) and configuration-interaction (CI) methods, perturbative CC schemes, and energy derivatives and response properties. The package also includes relativistic Hamiltonians for heavy-element systems and local correlation/cost-reduction techniques, allowing accurate calculations on medium-to-large molecules.
Installed versions
mrcc-2025-04-04 (also named as MRCC 25.1.0, complied with pcmsolver and libxc, recommended)
mrcc-2024-12-31 (complied with pcmsolver and libxc)
mrcc.2023-08-28 (binary)
Submitting an MRCC calculation
To run MRCC, the corresponding module must be loaded once per session:
module load mrcc/25.04.04
In this case, the job submission can be performed conveniently with the following command in the input location from the headnode:
MRCC250404 <number of processors> <Input file>
Entering only the script itself without arguments will print the help menu. The MRCC output file is saved in the same directory as the input file, with the only difference being its extension (.out). MRCC can run in parallel using OpenMP, MPI, or both. By default, the script sets up OpenMP for parallel execution. However, if the input file includes the “mpitasks” option, both MPI and OpenMP will be used together. The script is not designed to handle pure MPI runs. The number of MPI processes (or CPU cores) will match the value specified in the input file, with two OpenMP threads assigned to each core. When submitting the script, the number of processes must always specified on the command line. For OpenMP-only runs, this will correspond to the number of CPU threads. For MPI + OpenMP runs, this will correspond to the number of cores, and the number of threads will be automatically set. The default memory allocation is 2000MB unless a different value is defined in the input file using the “mem” keyword. Memory must always be specified in megabytes (MB) and refers to the total allocated memory, not memory per core.
An optional “-n” flag can be used to specify the number of nodes for MPI jobs:
MRCC250404 -n <number of nodes> <number of processors> <Input file>
For example:
MRCC250404 -o -n1 4 C2H6.inp
Additionally, the “-o” option can be used to optimize MPI job performance by allocating all CPUs on the node(s) to the job and increasing the number of threads. The extra processes beyond those specified by “mpitasks” are driver processes, which mostly run in the background and don’t require dedicated resources (though they will prevent other jobs from using those resources). For more details, refer to sections 9.2 and 9.3 of the MRCC manual. https://www.mrcc.hu/MRCC/manual/pdf/manual.pdf
An example MRCC input (C2H6.inp):
# CCSDT(Q) Single Point calculation
basis=cc-pVDZ
calc=CCSDT(Q)
mem=8000MB
mult=1
unit=angs
geom=xyz
8
C 0.765317 0.000000 0.000000
H 1.164483 1.006642 0.170694
H 1.164478 -0.355494 -0.957128
H 1.164488 -0.651149 0.786427
C -0.765317 0.000000 0.000000
H -1.164488 0.651723 -0.785951
H -1.164483 -1.006517 -0.171430
H -1.164478 0.354794 0.957387
Alternatively, MRCC can also be called via ORCA program package (version 5.0.4) as an interface. Whenever MRCC program used as an ORCA interface, only OpenMP is viable and the methods are restricted to single point energies but can also be used for rigid scan calculations or numerical frequencies.
Estimating computational requirements
There is no universal rule of thumb for the resource allocation of MRCC calculations, as the variety of chemical systems and theoretical methods have different resource demands. You need to develop the ability to independently estimate performance requirements. If you prefer to create your own specific SLURM script, you can invoke MRCC by pointing to /opt/software/packages/mrcc/20250404/.
You can find MRCC specific information at the following locations:
The generic references for MRCC
D. Mester, P. R. Nagy, J. Csóka, L. Gyevi-Nagy, P. B. Szabó, R. A. Horváth, K. Petrov, B. Hégely, B. Ladóczki, G. Samu, B. D. Lőrincz, and M. Kállay: Overview of Developments in the MRCC Program System, J. Phys. Chem. A 129, 2086 (2025).
MRCC, a quantum chemical program suite written by M. Kállay, P. R. Nagy, D. Mester, L. Gyevi-Nagy, J. Csóka, P. B. Szabó, Z. Rolik, G. Samu, B. Hégely, B. Ladóczki, K. Petrov, J. Csontos, Á. Ganyecz, I. Ladjánszki, L. Szegedy, M. Farkas, P. D. Mezei, R. A. Horváth, and B. D. Lőrincz. See www.mrcc.hu.
Please register at https://www.mrcc.hu/ to support the MRCC Developer Team. Your registration helps secure continued funding for the Team and directly contributes to further development of the software.
Last update by Milán SZŐRI: 2026-02-18