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Hybrid density functional calculation on the C240 Buckyball

This calculation involved performing a B3LYP direct SCF calculation on C240 without symmetry described by the cc-pVDZ basis set (3360 basis functions). These calculations were performed on Chinook on 512, 1024 and 2048 cores. The input file is available.


Parallel performance of Ab initio Molecular Dynamics using plane waves

Parallel performance of the CR-EOMCCSD(T) method (triples part)

An example of the scalability of the triples part of the CR-EOMCCSD(T) approach for Green Fluorescent Protein Chromophore (GFPC) described by cc-pVTZ basis set (648 basis functions) as obtained from NWChem. Timings were determined from calculations on the Franklin Cray-XT4 computer system at NERSC. See the Media:input_gfpc.nw input file for details.

Creomccsd t.png

Timings of CCSD/EOMCCSD for the oligoporphyrin dimer

CCSD/EOMCCSD timings for oligoporphyrin dimer (942 basis functions, 270 correlated electrons, D2h symmetry, excited-state calculations were performed for state of b1g symmetry, in all test calculation convergence threshold was relaxed, 1024 cores were used). See the Media:input_p2ta.nw input file for details.

 Iter          Residuum       Correlation     Cpu    Wall
   1   0.7187071521175  -7.9406033677717   640.9   807.7
  11   0.0009737920958  -7.9953441809574   691.1   822.2
 Iterations converged
 CCSD correlation energy / hartree =        -7.995344180957357
 CCSD total energy / hartree       =     -2418.570838364838890

 EOM-CCSD right-hand side iterations
      Residuum       Omega / hartree  Omega / eV    Cpu    Wall

Iteration   1 using    5 trial vectors
  0.7254630898708   0.2656229931076    7.22797  4471.5  5151.3

Iteration   2 using    6 trial vectors
  0.1584284659595   0.0882389635508    2.40111   865.3  1041.2

Current developments for high accuracy: GPGPU and alternative task schedulers

Currently various development efforts are underway for high accuracy methods that will be available in future releases of NWChem. The examples below shows the first results of the performance of the triples part of Reg-CCSD(T) on GPGPUs (left two examples) and of using alternative task schedules for the iterative CCSD and EOMCCSD.