A Force Field We Can Defend, Not Just Run
MMFF94 is now complete in the engine, built from all 16 parameter files of Halgren 1996 and checked against the published suite.
Where It Stands Live
MMFF94 runs in the engine since 0.7.0. Some Chemistry Lab screens still show Awaiting data while they are updated.
Built
Energy, minimisation, conformers, strain energy, charges and frequencies. Analytic first derivatives by forward-mode automatic differentiation; L-BFGS minimiser; MMFF94 bond-charge-increment charges.
Verified
Energy terms pass the published MMFF94 suite (761 molecules). Rotation, translation, net force and torque invariance below 1e-9.
Still Awaiting
UFF and Gasteiger charges wait for their parameter tables to be verified against the original papers.
Verified Terms and Speed
- Bond, angle, stretch-bend, out-of-plane, torsion and electrostatic terms: worst case 0.46 of the rounding bound
- Gradient errors against finite differences: 7e-8 to 1.5e-7 for MMFF94 and 2e-8 to 3.3e-8 kcal mol⁻¹ Å⁻¹ for the UFF terms, against a 1e-6 limit
- Nonbonded loops run on threads, AVX2 and CUDA; CUDA matches CPU to 7e-15
- A 6000-atom nonbonded evaluation took 98 ms on the CUDA server in two launches
- L-BFGS on the extended Rosenbrock function reaches 1 to within 1e-7 for n of 2, 10 and 100
Molecular Mechanics Questions
Can I run molecular mechanics today?
What is verified?
How complete is MMFF94?
Will you add AMBER, CHARMM, OPLS or GAFF?
Run Your Next Molecule Through AiMolSim
Connect your own server once, then let your team queue computations from the browser.