noqmc

Collection of nonorthogonal CI-QMC methods. Currently, nonorthogonal truncated CI-QMC and nonorthogonal truncated CCMC are available.

Installation

Clone the repository into a repository on your $PATH or $PYTHONPATH.

$ git clone https://github.com/m-baumgarten/noqmc.git

That's it.

Dependencies

In order to run noqmc properly, the following python modules are required:

• RevQCMagic
• pyblock
• PySCF

RevQCMagic can currently only be obtained by contacting Dr Alex Thom for access.

Before running a Calculation

In order to allow for a correct interpretation of Löwdin paired overlaps the RevQCMagic standards need to be adjusted accordingly. This can be done manually in path/to/RevQCMagic/qcmagic/auxiliary/qcmagic_standards.py. The following constants need to be changed:

ZERO_TOLERANCE = 1e-13
FLOAT_EPS = np.finfo(float).eps

Usage

To perform a simple NOCI-QMC calculation:

import noqmc.nomrciqmc as noci
from pyscf import gto

mol = gto.M(
    atom = [['H', 0, 0, 0],['H', 0, 0, 1.3]],
    basis = 'sto-3g', unit = 'Angstrom',
)

my_noci = noci.NOCIQMC(mol)
my_noci.run()

Similarly, to run a NOCCMC calculation:

import noqmc.nomrccmc as nocc
from pyscf import gto

mol = gto.M(
    atom = [['H', 0, 0, 0],['H', 0, 0, 1.3]],
    basis = 'sto-3g', unit = 'Angstrom',
)

my_nocc = nocc.NOCCMC(mol)
my_nocc.run()

However, it is advised to study the examples for improved convergence. Especially the NOCCMC method usually needs an accurate, system-specific set of parameters.

Documentation

A documentation can be generated from the docstrings with sphinx, similarly to the documentation in RevQCMagic. To do so, execute

$ cd docs

Now, make the api reference by executing

$ make html

Finally, the docs can be read from any webbrowser, e.g.

$ firefox build/html/index.html