From NWChem

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 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.

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
   2   0.2324364531569  -7.7250622086466   650.5   826.0
   3   0.1141748336279  -8.0072740512529   661.1   823.7
   4   0.0688913795193  -7.9503011202597   650.2   822.7
   5   0.0467548207575  -8.0036868822419   669.7   846.9
 MICROCYCLE DIIS UPDATE: 5 5
   6   0.0099626203484  -7.9968580114622   661.4   823.7
   7   0.0072165320866  -7.9945157146832   661.6   824.4
   8   0.0047936300464  -7.9945034979815   648.3   820.2
   9   0.0053957873651  -7.9949925734659   730.8   828.5
  10  0.0047996568854  -7.9950283121291   687.0   825.5
 MICROCYCLE DIIS UPDATE: 10 5
  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

Iteration   3 using    7 trial vectors
  0.0575982107592   0.0810948687618    2.20670   918.0  1042.2

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.

Scalability of the triples part of the Reg-CCSD(T) approach for Spiro cation described by the Sadlej's TZ basis set (POL1).

Speedup of GPU over CPU of the (T) part of the (T) part of the Reg-CCSD(T) approach as a function of the tile size for the uracil molecule.

Comparison of the CCSD/EOMCCSD iteration times for BacterioChlorophyll (BChl) for various tile sizes. Calculations were performed for 3-21G basis set (503 basis functions, C1 symmetry, 240 correlated electrons, 1020 cores).

Time per CCSD iteration for BChl in 6-311G basis set (733 basis functions, C1 symmetry, 240 correlated electrons, 1020 cores) as a function of tile size.

Scalability of the CCSD code for BChl in 6-311G basis set (733 basis functions; tilesize=40, C1 symmetry, 240 correlated electrons).