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ADDA > Euler angle rotation > beta, gammaに対して計算する

Last updated at Posted at 2017-12-08
動作環境
GeForce GTX 1070 (8GB)
ASRock Z170M Pro4S [Intel Z170chipset]
Ubuntu 16.04 LTS desktop amd64
TensorFlow v1.2.1
cuDNN v5.1 for Linux
CUDA v8.0
Python 3.5.2
IPython 6.0.0 -- An enhanced Interactive Python.
gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609
GNU bash, version 4.3.48(1)-release (x86_64-pc-linux-gnu)
scipy v0.19.1
geopandas v0.3.0
MATLAB R2017b (Home Edition)

ADDA

This article is related to ADDA (light scattering simulator based on the discrete dipole approximation).

非球形粒子の散乱特性を計算するADDAにおいて、粒子が様々な方向を向いて存在する状況を考慮したrandom orientation averagingの計算では、Euler angle rotationを用いる。

https://github.com/adda-team/adda/blob/master/doc/manual.pdf
last revised: Februrary 20, 2014
p21
8.2 Orientation averaging

Orientation averaging is performed over three Euler angles ($\alpha$, $\beta$, $\gamma$). Rotating over $\alpha$ is equivalent to rotating the scattering plane without changing the orientation of the scatterer relative to the incident radiation.

3つのEuler angleについてalpha関連の計算は、ADDAの1方向の計算で処理される(散乱面の計算がされる)ため、こちらでは実施しなくて良い。

残りのbeta, gammaに対して値を指定して計算することになる。

Euler angleのそれぞれの値の範囲は以下だろう。

  • gamma: [0, 360 deg.)
  • beta: [0, 180 deg.)
  • alpha: [0, 360 deg.)

betaは天頂角(polar angle)、gammaは方位角(azimuth angle)に対応するのかどうか。

manual.pdf
p58
B.2 avg_params.dat

using "zyz-notation"

p20
8.1 Single orientation

In short, coordinate axes attached to the particle are first rotated by the angle $\alpha$ over the z-axis, then by the angle $\beta$ over the current position of the y-axis (the line of nodes), and finally by the angle $\gamma$ over the new position of the z-axis (Fig. 5).

T-matrix for clusters of spheres

2008年の論文の計算実施時には、T-matrix for clusters of spheres (Multiple Sphere T Matrix code)を用いた。

こちらの場合、Euler anglesのうち、gamma方向の計算が1方向の計算内で実施されるため、alpha, gammaに対する方向指定で計算を行った。

下記のコードの旧バージョン(v1.0?)を用いていた。
http://eng.auburn.edu/users/dmckwski/scatcodes/

mstm-manual-2013-v3.0.pdf
p17
target_euler_angles_deg:

The Euler rotation first rotates each sphere $\theta_1$ about the z
axis, then rotates $\theta_2$ about the new y axis, then rotates $\theta_3$ about the new z axis.

こちらもADDAと同じ、zyz-notation。

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