schiff.md.in (3122B)
1 # Schiff 2 3 The Schiff program computes the *radiative properties* of soft 4 particles. 5 It uses the *Monte-Carlo* method to solve Maxwell's equations 6 within the 7 [L. Schiff's approximation](https://journals.aps.org/pr/abstract/10.1103/PhysRev.104.1481) 8 as presented in 9 [Charon et al. 2025](http://www.sciencedirect.com/science/article/pii/S0022407315003283). 10 The main advantages of using Monte-Carlo are: the possibility to address 11 *any shape* of particle, and the results are provided with a *numerical 12 accuracy*. 13 14 For a mixture of soft particles, Schiff estimates the total 15 *cross-sections* (absorption, scattering and extinction cross-sections) 16 in addition of the *phase function*, its cumulative and its inverse 17 cumulative. 18 19 The set of particles to simulate is defined by its *refractive index* - 20 provided at various wavelengths - and a *geometry distribution* that 21 controls how the particles look like into the mixture. 22 More precisely, this 23 distribution describes the main shapes of the particles (sphere, cylinder, 24 helical pipe, etc.) and their statistical variation according to the 25 distribution of their parameters (gaussian, lognormal, etc.). 26 27 [](images/particles.png) 28 29 > Examples of particle shapes handled by Schiff. 30 31 ## Related articles 32 33 - [Dauchet et al. 2023](https://doi.org/10.1364/OL.50048), 34 "Wave-scattering processes: path-integrals designed for the numerical 35 handling of complex geometries", Optics Letters 36 ([open access](https://arxiv.org/abs/2210.16146)) 37 38 - [Charon et al. 2016](http://www.sciencedirect.com/science/article/pii/S0022407315003283), 39 "Monte Carlo implementation of Schiff׳s approximation for estimating 40 radiative properties of homogeneous, simple-shaped and optically soft 41 particles: Application to photosynthetic micro-organisms", Journal of 42 Quantitative Spectroscopy and Radiative Transfer 43 ([open access](https://hal.science/hal-01599991v1/)) 44 45 - [Weitz et al. 2016](https://www.sciencedirect.com/science/article/abs/pii/S002199911630393X), 46 "Monte Carlo efficiency improvement by multiple sampling of 47 conditioned integration variables", Journal of Computational Physics 48 ([open access](https://hal.science/hal-01599986/)) 49 50 ## A straight interface 51 52 The Schiff program is a *command-line tool* that processes input data, 53 performs computations, write results and that's all. 54 It makes no assumptions on how the input data are created excepted that 55 it has to follow the expected file formats. 56 The simulation results are also provided as is, in a raw ASCII format. 57 58 This thin interface is particularly well suited to be *extended* and 59 *integrated into any toolchain*. 60 According to the user needs, the optical properties of the particles can be 61 entered manually or generated by an external program. 62 In the same way, the output data can either be directly interpreted or 63 post-processed by any script with respect to the targeted toolchain. 64 65 ## History 66 67 `schiff` was funded from 2015 to 2016 by the ALGUE project, which was 68 supported by the [IDEX program](https://anr.fr/ProjetIA-11-IDEX-0002). 69 |Méso|Star> was sub-contractor of the project.