Interface to DKH by A. Wolf, M. Reiher, and B. A. Hess

Code author: Justin M. Turney

Section author: Justin M. Turney

Module: Keywords, Samples

Installation

Binary

• 

• DKH is available as a conda package for Linux and macOS (and Windows, through the Ubuntu shell).

• If using the PSI4 binary, dkh has already been installed alongside.

• If using PSI4 built from source, and anaconda or miniconda has already been installed (instructions at Quick Installation), dkh can be obtained through conda install dkh. Then enable it as a feature with ENABLE_dkh, hint its location with CMAKE_PREFIX_PATH, and rebuild PSI4 to detect dkh and activate dependent code.

• To remove a conda installation, conda remove dkh.

Source

• 

• If using PSI4 built from source and you want dkh built from from source also, enable it as a feature with ENABLE_dkh, and let the build system fetch and build it and activate dependent code.

Input

For all electron calculations one can use the Douglas-Kroll-Hess (DKH) Hamiltonian to take into account scalar relativistic effects.

Minimal input for DKH single-point computation looks like this:

molecule {
Mg
}

set basis aug-cc-pvdz-dk
set relativistic dkh

energy('scf')

By default a 2nd-order DKH calculation is performed. To change the default order use the DKH_ORDER option. The version of the code found in PSI4 is capable of up to 4th-order DKH calculations.

Keywords

RELATIVISTIC

Relativistic Hamiltonian type

• Type: string
• Possible Values: NO, X2C
• Default: NO

DKH_ORDER

Order of Douglas-Kroll-Hess

• Type: integer
• Default: 2

Reference

When using this code please make reference to the appropriate following paper:

• “The Generalized Douglas-Kroll Transformation,” A. Wolf, M. Reiher, and B. A. Hess, J. Chem. Phys. 117, 9215 (2002). (doi: 10.1063/1.1515314)

How to configure dkh for building Psi4

Role and Dependencies

• Role — In PSI4, DKH is a library that provides additional quantum chemical capabilities (relativistic effects).
• Downstream Dependencies — PSI4 (\(\Leftarrow\) optional) dkh
• Upstream Dependencies — dkh \(\Leftarrow\) Fortran

CMake Variables

• ENABLE_dkh — CMake variable toggling whether Psi4 builds with dkh
• CMAKE_PREFIX_PATH — CMake list variable to specify where pre-built dependencies can be found. For dkh, set to an installation directory containing include/DKH/DKH_MANGLE.h
• dkh_DIR — CMake variable to specify where pre-built dkh can be found. Set to installation directory containing share/cmake/dkh/dkhConfig.cmake
• CMAKE_DISABLE_FIND_PACKAGE_dkh — CMake variable to force internal build of dkh instead of detecting pre-built

Examples

1. Build bundled

>>> cmake -DENABLE_dkh=ON

2. Build without dkh

>>> cmake

3. Link against pre-built

>>> cmake -DENABLE_dkh=ON -DCMAKE_PREFIX_PATH=/path/to/dkh/root

>>> cmake -DENABLE_dkh=ON -Ddkh_DIR=/path/to/dkh/configdir

4. Build bundled despite pre-built being detectable

>>> cmake -DENABLE_dkh=ON -DCMAKE_PREFIX_PATH=/path/to/unwanted/dkh/root/and/wanted/other/dependencies/root -DCMAKE_DISABLE_FIND_PACKAGE_dkh=ON