chi1chi2 0.1.1

set of scripts for calculating linear and nonlinear optical properties of organic crystals

The aim of the program is to calculate linear (refractive indices) and nonlinear (\(\chi^2\) for second harmonic generation) optical properties of organic crystals.

Contents

• Installation

• Description

• Step 1 - Input preparation

• Step 1a after geometry optimization

• Step 2 - property calculation

• Step 3 - core calculations

• Step 4 - result analysis

• Examples

Installation

Make sure you have installed:

• gfortran

• python 3.6

• open babel

Installation:

• pip install chi1chi2

• for the fortran programs a Makefile is provided with the repository: make command builds the programs in the build/ directory

Description

The whole program constitutes a set of scripts that need to be executed in order.

There are four main steps:

1. Input preparation (optionally - geometry optimization)

2. Optical properties of molecular sub-units calculations

3. Calculations of bulk properties

4. Analysis of the results

The purpose of this file is to lead the user through all these steps.

Step 1 - Input preparation

1. from Cif (easy path)

   use chi.from_cif to get geometry for further optimization with e.g. crystal09/14/..

2. from fractional coordinates

   use chi.from_fra script (see: examples/mna_cif.fra, examples/mna_cif2.fra to see the convention)

   (remember to adjust the

3. manually

   see examples for the convention

Step 1a after geometry optimization

4. use chi.from_crystal script to adjust the coordinates and charges after crystal geometry optimization

5. run chi.input_preparator script to get input files for:

   • charge_generator program (example usage: charge_generator < chg1.inp)

   • Lorentz tensor with lorentz program (example usage: lorentz < lorentz.inp > L.dat)

Step 2 - property calculation

Use sets of charges, geometries and follow your favorite property calculation procedure. Additional shell scripts could be provided in later releases.

Step 3 - core calculations

Use script chi.main to get the \(\chi^1\) and \(\chi^2\) tensor components in the so called ab’c* reference frame.

v 0.1.1: Q-LFT calculations enabled!

Step 4 - result analysis

This step will be provided in future releases.

• Refractive indices and optical indicatrix analysis (0.2.0)

• Magnitude of the \(\chi^2\) tensor components in the direction of the optical indicatrix (0.2.0)

• Phase matching diagrams (in future plans)

Examples

See the examples/examples.pdf to follow the steps used in the integration tests. The files used for the tests are located in the tests/integration directory:

• input as a starting point

• expected as a reference