General

Overview

GOUDA (GPU-Oriented Ultrafast DFT for AMS) is an AMS engine for GPU-accelerated molecular electronic structure calculations. It uses Gaussian-type orbital basis sets and the cuEST library for the computationally intensive parts of Hartree–Fock and DFT calculations.

GOUDA calculates energies and analytical nuclear gradients. You can therefore use it with AMS driver tasks such as single-point calculations, geometry optimizations, and numerical frequencies. The engine also supports Mulliken charges, dipole moments, static polarizabilities, molecular orbital information, and selected TDA or TDDFT excitation calculations.

Current limitations

  • GOUDA supports non-periodic systems only.

  • GOUDA requires an AMS build with cuEST support and an NVIDIA GPU with CUDA compute capability 8.0 or newer.

  • Response calculations require a closed-shell, integer-occupation, gas-phase reference and a supported exchange-correlation functional.

  • Only static polarizabilities are available.

  • Full TDDFT is available only for pure functionals. TDA also supports the hybrid functionals accepted by the response implementation.

Basic input

Select GOUDA in the Engine block of an AMS input file. The following example calculates the PBE/def2-SVP energy of a water molecule:

Task SinglePoint

System
   Atoms
      O  0.000000  0.000000  0.000000
      H  0.758602  0.000000  0.504284
      H -0.758602  0.000000  0.504284
   End
End

Engine GOUDA
   XCFunctional PBE
   Basis
      Type def2-svp
   End
EndEngine

The AMS driver controls the molecular geometry, task, and requested properties. The GOUDA block controls the electronic structure method, basis sets, SCF procedure, and GPU memory usage. See the AMS manual for driver-level input.