List of Folding@home cores
The distributed-computing project Folding@home uses scientific computer programs, referred to as "cores" or "fahcores", to perform calculations. Folding@home's cores are based on modified and optimized versions of molecular simulation programs for calculation, including TINKER, GROMACS, AMBER, CPMD, SHARPEN, ProtoMol and Desmond. These variants are each given an arbitrary identifier (Core xx). While the same core can be used by various versions of the client, separating the core from the client enables the scientific methods to be updated automatically as needed without a client update.
These cores listed below are currently used by the project.
GROMACS, short for GROningen MAchine for Chemical Simulations, is an GPL open source molecular dynamics simulation package originally developed in the University of Groningen, and currently maintained by several universities and institutions worldwide. Gromacs is extremely optimized, with built-in consistency checking and continual ETA estimates, and is primarily designed for biochemical molecules with complicated bonding interactions such as proteins, lipids and nucleic acids. Gromacs calculations are single precision, but it is used extensively throughout the project. Folding@home has been granted a non-commercial, non-GPL license for Gromacs, and is thus not required to release its source code. All variants use SIMD optimizations including SSE on Intel processors, 3DNow+ on AMD chips and AltiVec on PowerPC processors. This allows for a very significant speed increase over TINKER-based cores.
- Gromacs (Core 78)
- Gromacs 33 (Core a0)
- Gromacs SREM (Core 80)
- GroSimT (Core 81)
- This core performs simulated tempering, of which the basic idea is to enhance sampling by periodically raising and lowering temperature. This may allow Folding@home to more efficiently sample the transitions between folded and unfolded conformations of proteins. Available for Windows and Linux uniprocessor clients only.
- DGromacs (Core 79)
- DGromacsB (Core 7b)
- DGromacsC (Core 7c)
- Very similar to Core 79, and initially released for Linux and Windows in April 2008 for Windows, Linux, and macOS uniprocessor clients.
- GB Gromacs (Core 7a)
- GB Gromacs (Core a4)
- SMP2 (Core a3)
- SMP2 bigadv (Core a5)
- SMP2 bigadv (Core a6)
- A newer version of the a5 core.
- Core a7
Cores for the Graphics Processing Unit use the graphics chip of modern video cards to do molecular dynamics. The GPU Gromacs core is not a true port of Gromacs, but rather key elements from Gromacs were taken and enhanced for GPU capabilities.
These are the second generation GPU cores. Unlike the retired GPU1 cores, these variants are for ATI CAL-enabled 2xxx/3xxx or later series and NVIDIA CUDA-enabled NVIDIA 8xxx or later series GPUs.
- GPU2 (Core 11)
- GPU2 (Core 12)
- Available for x86 Windows clients only.
- GPU2 (Core 13)
- Available for x86 Windows clients only.
- GPU2 (Core 14)
These are the third generation GPU cores, and are based on OpenMM, Pande Group's own open library for molecular simulation. Although based on the GPU2 code, this adds stability and new capabilities.
- GPU3 (core 15)
- Available to x86 Windows only.
- GPU3 (core 16)
- GPU3 (core 17) 
- Available to Windows and Linux for AMD and NVIDIA GPUs using OpenCL. Much better performance because of OpenMM 5.1
- GPU3 (core 18)
- Available to Windows for AMD and NVIDIA GPUs using OpenCL. This core was developed to address some critical scientific issues in Core17  and uses the latest technology from OpenMM 6.0.1. There are currently issues regarding the stability and performance of this core on some AMD and NVIDIA Maxwell GPUs. This is why assignment of work units running on this core has been temporarily stopped for some GPUs.
- GPU3 (core 21)
- Available to Windows and Linux for AMD and NVIDIA GPUs using OpenCL or CUDA. It uses OpenMM 6.2 and fixes the Core 18 AMD/NVIDIA performance issues. [Source]
Short for Assisted Model Building with Energy Refinement, AMBER is a family of force fields for molecular dynamics, as well as the name for the software package that simulates these force fields. AMBER was originally developed by Peter Kollman at the University of California, San Francisco, and is currently maintained by professors at various universities. The double-precision AMBER core is not currently optimized with SSE nor SSE2, but AMBER is significantly faster than Tinker cores and adds some functionality which cannot be performed using Gromacs cores.
- PMD (Core 82)
- Available for Windows and Linux uniprocessor clients only.
ProtoMol is an object-oriented, component based, framework for molecular dynamics (MD) simulations. ProtoMol offers high flexibility, easy extendibility and maintenance, and high performance demands, including parallelization. In 2009, the Pande Group was working on a complementary new technique called Normal Mode Langevin Dynamics which had the possibility to greatly speed simulations while maintaining the same accuracy.
- ProtoMol Core (Core b4)
- Available to Linux x86/64 and x86 Windows.
These cores are not currently used by the project, as they are either retired due to becoming obsolete, or are not yet ready for general release.
TINKER is a computer software application for molecular dynamics simulation with a complete and general package for molecular mechanics and molecular dynamics, with some special features for biopolymers.
- Tinker core (Core 65)
- An unoptimized uniprocessor core, this was officially retired as the AMBER and Gromacs cores perform the same tasks much faster. This core was available for Windows, Linux, and Macs.
- GroGPU (Core 10)
- Gro-SMP (Core a1)
- GroCVS (Core a2)
- Available only to x86 Macs and x86/64 Linux, this core is very similar to Core a1, as it uses much of the same core base, including use of MPI. However, this core utilizes more recent Gromacs code, and supports more features such as extra-large work units. Officially retired due to move to a threads-based SMP2 client.
- Also known as the SCEARD core, this variant was for the PlayStation 3 game system, which supported a Folding@Home client until it was retired in November 2012. This core performed implicit solvation calculations like the GPU cores, but was also capable of running explicit solvent calculations like the CPU cores, and took the middle ground between the inflexible high-speed GPU cores and flexible low-speed CPU cores. This core used SPE cores for optimization, but did not support SIMD.
Short for Car–Parrinello Molecular Dynamics, this core performs ab-initio quantum mechanical molecular dynamics. Unlike classical molecular dynamics calculations which use a force field approach, CPMD includes the motion of electrons in the calculations of energy, forces and motion. Quantum chemical calculations have the possibility to yield a very reliable potential energy surface, and can naturally incorporate multi-body interactions.
- QMD (Core 96)
- This is a double-precision variant for Windows and Linux uniprocessor clients. This core is currently "on hold" due to the main QMD developer, Young Min Rhee, graduating in 2006. This core can use a substantial amount of memory, and was only available to machines that chose to "opt in". SSE2 optimization on Intel CPUs is supported. Due to licensing issues involving Intel libraries and SSE2, QMD Work Units were not assigned to AMD CPUs.
- SHARPEN Core
- In early 2010 Vijay Pande said "We've put SHARPEN on hold for now. No ETA to give, sorry. Pushing it further depends a lot on the scientific needs at the time." This core uses different format to standard F@H cores, in that there is more than one "Work Unit" (using the normal definition) in each work packet sent to clients.
The software for this core was developed at D. E. Shaw Research. Desmond performs high-speed molecular dynamics simulations of biological systems on conventional computer clusters. The code uses novel parallel algorithms and numerical techniques to achieve high performance on platforms containing a large number of processors, but may also be executed on a single computer. Desmond and its source code are available without cost for non-commercial use by universities and other not-for-profit research institutions.
- Desmond Core
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- "QMD FAQ" (FAQ). 2007. Retrieved 2011-08-28.
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- "SHARPEN". Archived from the original on December 2, 2008.
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