EmbeddingIntegralGenerator

Generator of embedding integrals in different formats to allow for reading with different quantum chemistry codes like TigerCI, Molpro, Molcas, etc.

Currently available (To be continued):

• Molpro
• TigerCI
• GAMESS
• MOLCAS
• QChem
• PySCF

Needs basis set specification, molecular structure, embedding potential, and grid information.

Compilation

Cmake based build system. Intel compilers can be replaced with gnu compilers but not tested.

1. Configure with

    CC=icc CXX=icpc cmake <path to src> -DCMAKE_BUILD_TYPE=<Debug or Release> -DOMP=<On or Off>
   

   For production calculations use -DCMAKE_BUILD_TYPE=Release and -DOMP=On

2. Compile with

    make -j <number of threads>
   

Usage

To run the code call it with an input file as parameter

emb_ints.exe <input file> > <output file>

Currently, two output formats are possible (TIGERCI and MOLPRO, see below for details). For a list of keywords and examples see below.

Examples

• Example input files are included in the folder "examples".
• There are two examples each for every output format.
• In the case of Molpro, examples for interfacing with a HF calculation are included and the files "reference_energies_molcas" contain HF energies obtained with and without the potential from Molcas for comparison.
• The embedding potential applied in these calculations was generated from random numbers.

Tests

To be added. So far only files with reference energies from Molcas have been included with the example for the Molpro interface.

List of keywords

• GRID DIMENSIONS

  • Three integers on the following line to specify grid dimension in x, y, z direction
  • Required

• LATTICE VECTORS

  • The lattice vectors in x, y, z, direction on the next three lines
  • Required

• SHIFT VECTOR

  • Specifies the shift vector on the next line
  • Default: 0.0 0.0 0.0
  • Use with care, not well tested

• XYZ FILE

  • xyz file containing geometry information
  • Required

• BASIS FILE

  • file with basis set in Molcas format

  • all-electron nuclear charge has to be specified even when using an ECP (old format)

  • include the basis set only (remove the ECP block)

  • REMOVE ALL instances of lines:

    cartesian d

    End of basis set

  • Required

• EMBEDDING POTENTIAL FILE

  • file containing the embedding potential on the specified grid
  • Required

• OUTPUT FORMAT

  • string specifying the desired output format for the embedding integrals
  • available: MOLPRO, TIGERCI, GAMESS, MOLCAS, QCHEM, PYSCF

• AO INTEGRAL THRESHOLD (not working yet)

  • Planned to be threshold for printing integrals
  • Default: 1.0e-12

• CARTESIAN

  • Flag switching to cartesian instead of spherical basis functions
  • Not fully supported use with care. Will be improved in future.

• EMBEDDING INTS REAL

  • Flag switching to old (depreciated) version of the integration scheme purely in real space

• NUM THREADS

  • Number of threads to use
  • Default: 1