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LICHEM: Layered Interacting CHEmical Models

By: Eric G. Kratz

Symbiotic Computational Chemistry


LICHEM: A QM/MM interface for polarizable force fields

GPL license

Automated tests

Travis CI build: Build Status


This package is an open-source (GPLv3) interface between QM and MM software so that QM/MM calculations can be performed with polarizable and frozen electron density force fields. Functionality is also present for standard point-charge based force fields, pure MM, and pure QM calculations.

Available calculations: single-point energies, geometry optimizations, classical Monte Carlo, path-integral Monte Carlo, and reaction pathways.

Available QM wrappers: Gaussian, NWChem, PSI4

Available MM wrappers: TINKER

MM wrappers in development: LAMMPS


If you use LICHEM in your research, please cite the following papers:

Kratz, E.G.; Walker, A.R.; Lagardere, L; Lipparini, F; Piquemal, J.-P.; and
Cisneros, G.A.; "LICHEM: A QM/MM Program for Simulations with Multipolar and
Polarizable Force Fields", J. Comput. Chem., 37, 11, 1019, (2016)
Kratz, E.G.; Duke, R.E.; and Cisneros, G.A.; "Long-Range Electrostatic
Corrections in Multipolar/Polarizable QM/MM Simulations", Theor. Chem. Acc.,
135, 7, 1, (2016)


Currently, the binary and user's manual are not included in the repository. However, the Makefile can be used to generate both files. Since LICHEM is designed to be simple, only a small number of packages are required to compile the code. An approximate list of packages is given below.

 LICHEM binary: OpenMP
 LICHEM test suite: Python
 LICHEM manual: LaTeX, BibTeX, TeXLive

A copy of the Eigen3 library is included with the LICHEM source code. However, other versions of Eigen3 can be used to build LICHEM by modifying the Makefile.

To install LICHEM, clone the git repository:

user:$ mkdir LICHEM
user:$ git clone ./LICHEM/

On Ubuntu boxes, the Makefile should function without modifications. However, it may be necessary to install additional LaTeX packages. On OSX machines, the SEDI, TEX, BIB, and CXXFLAGS variables will need to be modified.

The Makefile can produce both the documentation and the binary.

user:$ make install

For development, debugging, or testing an alternate binary can be compiled.

user:$ make Dev

Additional make rules can be found in the Makefile.

QM and MM packages

LICHEM uses QM and MM packages that are pre-installed and located in the user's path. The LICHEM wrappers are kept up-to-date with the development of the QM and MM packages. It is best to use packages from conda, git, or other package management systems.


LICHEM is still in the early stages of development. Please report all bugs so that the code can be updated quickly. Bugs should be reported through the GitHub issues interface. A list of known issues and the development timeline are available in the doc directory or on the GitHub page.

Development versions of LICHEM are kept in a private repository. Large changes to the code or the addition of new features (diffuse charges, reaction path ways, etc) are tested and published before they are merged into the public repository. To ensure that LICHEM compiles properly, dummy function calls are added for incomplete or untested features.

Relatively minor updates (documentation, output printing, bug fixes, comments, etc) are released ASAP. Updates from the private development branch are generally merged into the public repository as a single commit.

Further development details can be found in the doc directory, or the GitHub issues section.


Jokes and Easter eggs can be included by changing

 const bool JOKES = 0; //Print humorous comments

in LICHEM_options.h to

 const bool JOKES = 1; //Print humorous comments

before compiling the code.

Black-box testing

Test calculations can be performed with the runtests script in the tests directory. While the tests do not cover all of the LICHEM functionality, the test suite can detect installation errors. If tests are consistently failing, please post details on the GitHub issues section.

Tests can be performed for pairs of QM and MM wrappers.

user:$ ./runtests Ncpus QMPackage MMPackage

Additionally, tests can be run for all wrappers at once.

user:$ ./runtests Ncpus All

A dry run can be performed to check packages without performing the calculations.

user:$ ./runtests Ncpus QMPackage MMPackage Dry

White-box testing

Tools for performing static code analysis can be found in the tests/Code_analysis directory. These tools can help developers detect coding errors and style issues.

A copy of Google's cpplint tool can be run with the RunLint script.

user:$ ./RunLint

The script produces a file named LintTest.log containing some stylistic deviations from the Google style guide. LICHEM does not conform to the Google style guide, but the analysis can be useful to developers.

A configuration file for cppcheck is also included in the tool kit.

user:$ cppcheck-gui lichem.cfg

In addition to using cpplint and cppcheck, the Makefile can be used to check for code issues at compile-time.

user:$ make checksyntax


user:$ make Dev

The two commands above check for compiler warnings using the c++14 standard.


The development of LICHEM was supported by funding from the NIH (Grant No. R01GM108583) and Wayne State University. LICHEM is currently maintained by both Eric G. Kratz and the Cisneros research group at University of North Texas.


  • Eric G. Kratz
  • Cisneros group, University of North Texas