# Examples¶

WARNING: THESE EXAMPLES ARE NOT CONVERGED! YOU MUST CONVERGE PARAMETERS (SIMULATION CELL SIZE, JASTROW PARAMETER NUMBER/CUTOFF, TWIST NUMBER, DMC TIME STEP, DFT PLANE WAVE CUTOFF, DFT K-POINT MESH, ETC.) FOR REAL CALCUATIONS!

The following examples should run in serial on a modern workstation in a few hours.

## Using QMCPACK directly¶

In examples/molecules are the following examples. Each directory also contains a README file with more details.

 Directory Description H20 H2O molecule from GAMESS orbitals He Helium atom with simple wavefunctions

## Using Nexus¶

For more information about Nexus, see the User Guide in nexus/documentation.

For Python to find the Nexus library, the PYTHONPATH environment variable should be set to <QMCPACK source>/nexus/library. For these examples to work properly, the executables for QE and QMCPACK either need to be on the path, or the paths in the script should be adjusted.

These examples can be found under the nexus/examples/qmcpack directory.

 Directory Description diamond Bulk diamond with VMC graphene Graphene sheet with DMC c20 C20 cage molecule oxygen_dimer Binding curve for O$$_2$$ molecule H2O H$$_2$$O molecule with QE orbitals LiH LiH crystal with QE orbitals