Incremental Scheme

Description

APTS is a program written by Jun Zhang for performing accurate and efficient correlation calculations for large molecules by incremental scheme. In brief, APTS can decompose a large molecule into several fragments, perform the correlation calculation for each fragment and combine the results to produce the final total energy. The essential approach in APTS is called incN-db-B0 (Nth-order incremetal dual-basis set zero-buffer). With the help of APTS, one can perform very large calculations, say, CCSD(T) with 1000 basis functions, using ordinary hardware (like 50 CPU cores). Below are some of its characters:

Can perform CCSD, CCSD(T), CCSD(T)-F12 calculations for both closed- and open shell molecules.
The program can be run in a black-box way: You need only to feed APTS with the geometry, charge and spin of the molecule and the method, basis set.
High accuracy and efficiency: In the best case the calculation can be speeded up by 100 times with error less than 0.1 kcal/mol!

Citation

When you use APTS in your work, I will appreciate you if you can cite the following publication:

Zhang, J.; Dolg, M. Third-order Incremental Dual-basis Set Zero-buffer Approach: An Accurate and Efficient Way to Obtain CCSD and CCSD(T) Energies. J. Chem. Theory Comput. 2013, 9, 2992-3003.

If you use APTS to do F12 calculations or for open shell molecules, please cite the following publications:

Zhang, J.; Dolg, M. Approaching the Complete Basis Set Limit of CCSD(T) for Large Systems by the Third-order Incremental Dual-basis Set Zero-buffer F12 Method. J. Chem. Phys. 2014, 140, 044114.
Zhang, J.; Dolg, M. Third-order Incremental Dual-basis Set Zero-buffer Approach for Large High-spin Open-shell Systems. J. Chem. Theory Comput. 2015, 11, 962-968.

Availability

APTS can only be run in Linux with Molpro. You must have Molpro with a valid license. Please contact Jun Zhang for this code.