Introduction

TeraChem is general purpose quantum chemistry software designed to run on Nvidia CUDA-enabled GPU architectures under a 64-bit Linux operating system. Some of TeraChem features include:

1. Restricted, unrestricted, and restricted open shell Hartree-Fock and grid-based Kohn-Sham ground state energy and gradient calculations
2. Time-dependent density functional theory (TDDFT) and Configuration Interaction Singles (CIS) treatment of excited state energies and gradients.
3. Restricted ensemble Kohn-Sham, i.e. SI-SA-REKS(2/2), treatment of excited state energies and gradients.
4. Full support of s, p and d-type atom-centered Gaussian basis functions, and effective core potentials with angular momentum of up to L=4.
5. Various DFT functionals, including range-corrected and Coulomb attenuated functionals (BLYP, B3LYP, PBE, PBE0, $$\omega$$PBE, $$\omega$$PBEh, $$\omega$$B97, $$\omega$$B97x, camB3LYP, etc) and DFT grids (800 - 80,000 grid points per atom)
6. Static grid (single grid used for the entire calculation) and dynamical grid (multigrid) integration.
7. Empirical dispersion correction (DFT-D3 and DFT-D2)
8. Polarizable Continuum Models for solvation
9. Geometry optimization (L-BFGS, Conjugate gradient, Steepest descent)
   1. The optimization can be carried out either in Cartesian or internal coordinates as specified in the start file (all input geometries are provided in Cartesians). The Cartesian->internal-> Cartesian coordinate transformation is performed automatically whenever required.
   2. Constrained optimization with frozen atoms, constrained bond lengths, angles, and dihedrals.
   3. Transition state search (Nudged elastic band) in internal and Cartesian coordinates
10. Ab initio molecular dynamics (NVE, NVT ensembles)
    1. Reversible Born-Oppenheimer dynamics
    2. Spherical boundary conditions
11. Support for multiple-GPU systems
12. Single/Dynamical/Double precision accuracy
13. QM/MM treatment of surrounding water molecules using TIP3P ¹force field
14. Natural bond orbital analysis through integration with NBO6
15. Polarizabilities for HF and closed-shell DFT methods
16. Runs on up to 16 GPUs in the same node in parallel, not parallelized to run on multiple nodes
17. Semiempirical methods including GFN-xTB. A unique feature of TeraChem is that all ab initio methods can be executed with semiempirical integrals (for example, semiempirical CASSCF). Also, the semiempirical integrals are GPU-accelerated.
18. Connection with Amber for QM/MM calculations of biological molecules.

Footnotes

1. W. L. Jorgensen, J. Chandrasekha, J. D. Madura, R. W. Impey, and M. L. Klein, J. Chem. Phys. 79 926 (1983) ↩