https://github.com/pierre-24/check-sos
Let's figure out SOS
https://github.com/pierre-24/check-sos
Last synced: 2 months ago
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Let's figure out SOS
- Host: GitHub
- URL: https://github.com/pierre-24/check-sos
- Owner: pierre-24
- License: mit
- Created: 2024-10-29T13:24:55.000Z (7 months ago)
- Default Branch: main
- Last Pushed: 2024-12-20T09:15:01.000Z (5 months ago)
- Last Synced: 2025-01-26T05:24:35.136Z (4 months ago)
- Language: TeX
- Size: 3.17 MB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# check-sos
Let's figure out SOS... Once again ;)
## Overview
Based on perturbation theory, the sum-over-states (SOS) expression of Orr and Ward states that any component of any nonlinear optical tensor can be computed as a sum involving ground-to-excited and excited-to-excited state contributions ([details here](white-papers/SOS.pdf)).
While straightforward to implement, this expression introduces two types of divergences: **secular divergences** and **resonances**.
Resonances are intrinsic to perturbation theory, while secular divergences are mathematical artifacts that should be avoided.
This project provides a (non-efficient) implementation of non-divergent formulas, tested against the divergent versions.
The input files used are in the format defined by MultiWFN (refer to Section 3.27.2.1 of the [MultiWFN manual](http://sobereva.com/multiwfn/misc/Multiwfn_3.8_dev.pdf)).
These files can be generated using system models based on the VB-nCT theory, which also allows for validation of the results (see [this document](white-papers/few-states.pdf)).
## Installation
Install the package easily with:
```bash
pip install git+https://github.com/pierre-24/check-sos.git
```
## Usage
**Note:** these program generally use atomic unit as input and output. The `--eV` option only affects excitation energies.
In order to compute a nonlinear tensor using SOS, use:
```bash
sos-get-tensor -i tests/2-state.txt
```
Inputs are:
+ `-i`: input file in the MultiWFN format. Use `--eV` if the excitation energies are give in eV.
+ `-w` for the laser frequency, in atomic unit (default is 0).
+ `-f` for a space-separated list of input field. (default is `-f "1 1"`) For example, to compute $\beta(-2\omega;\omega,\omega)$ (SHG phenomenon), use `-f "1 1"`. For $\gamma(-\omega;\omega,-\omega,\omega)$, use `-f "1 -1 1"`. The value of $\omega$ is given by `-w`.
The output is the tensor.
To create an input file using a simple VB-nCT model, use:
```bash
sos-create-system tests/CT_dipoles.txt -t .05 -T .01 -m 0.2
```
Inputs are:
+ An input file, which contains a list of CT dipoles (3 values per line, being X, Y, and Z).
+ `-t`, `-T` and `-m`: values for $t$, $T$ and $m_{CT}$, as described in Section 2.3 of [this document](white-papers/few-states.pdf). All in atomic units.
+ `--eV` to output energies in eV rather than atomic unit, which is the default.
The output is a text file for SOS in the MultiWFN format, which can thus be used by `sos-get-tensor`.
It is possible to combine both commands:
```bash
sos-create-system tests/CT_dipoles.txt -t .05 -T .01 -m 0.2 | sos-get-tensor -f "-1 1"
```
... Which will compute the optical rectification tensor :)