Changeset d4117ccb in sasview
- Timestamp:
- Apr 16, 2014 5:00:07 AM (11 years ago)
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- 1127c32
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src/sans/models/media/model_functions.rst
r1127c32 rd4117ccb 195 195 196 196 - LamellarPCrystalModel_ 197 - SCCrystalModel 198 - FCCrystalModel 199 - BCCrystalModel 197 - SCCrystalModel_ 198 - FCCrystalModel_ 199 - BCCrystalModel_ 200 200 201 201 Parallelpipeds … … 2613 2613 2614 2614 Here, the scale factor is used instead of the mass per area of the bilayer (*G*). The scale factor is the volume 2615 fraction of the material in the bilayer, *not* the total excluded volume of the paracrystal. *Z N(q)* describes the2616 interference effects for aggregates consisting of more than one bilayer. The equations used are (3-5) from the 2617 Bergstrom reference below.2615 fraction of the material in the bilayer, *not* the total excluded volume of the paracrystal. *Z*\ :sub:`N`\ *(q)* 2616 describes the interference effects for aggregates consisting of more than one bilayer. The equations used are (3-5) 2617 from the Bergstrom reference below. 2618 2618 2619 2619 Non-integer numbers of stacks are calculated as a linear combination of the lower and higher values … … 2657 2657 **2.1.34. SCCrystalModel** 2658 2658 2659 Calculates the scattering from a simple cubic lattice with 2660 paracrystalline distortion. Thermal vibrations are considered to be 2661 negligible, and the size of the paracrystal is infinitely large. 2662 Paracrystalline distortion is assumed to be isotropic and 2663 characterized by a Gaussian distribution. 2659 Calculates the scattering from a **simple cubic lattice** with paracrystalline distortion. Thermal vibrations are 2660 considered to be negligible, and the size of the paracrystal is infinitely large. Paracrystalline distortion is assumed 2661 to be isotropic and characterized by a Gaussian distribution. 2664 2662 2665 2663 The returned value is scaled to units of |cm^-1|\ |sr^-1|, absolute scale. 2666 2664 2665 *2.1.34.1. Definition* 2666 2667 2667 The scattering intensity I(q) is calculated as 2668 2668 2669 2670 2671 where scale is the volume fraction of spheres, Vp is the volume of the 2672 primary particle, V(lattice) is a volume correction for the crystal 2673 structure, P(q) is the form factor of the sphere (normalized) and Z(q) 2674 is the paracrystalline structure factor for a simple cubic structure. 2675 Equation (16) of the 1987 reference is used to calculate Z(q), using 2676 equations (13)-(15) from the 1987 paper for Z1, Z2, and Z3. 2677 2678 The lattice correction (the occupied volume of the lattice) for a 2679 simple cubic structure of particles of radius R and nearest neighbor 2680 separation D is: 2681 2682 2683 2684 The distortion factor (one standard deviation) of the paracrystal is 2685 included in the calculation of Z(q): 2686 2687 2688 2689 where g is a fractional distortion based on the nearest neighbor 2690 distance. 2691 2692 The simple cubic lattice is: 2693 2694 2695 2696 For a crystal, diffraction peaks appear at reduced q-values givn by: 2697 2698 2699 2700 where for a simple cubic lattice any h, k, l are allowed and none are 2701 forbidden. Thus the peak positions correspond to (just the first 5): 2702 2703 2704 2705 NB: The calculation of Z(q) is a double numerical integral that must 2706 be carried out with a high density of points to properly capture the 2707 sharp peaks of the paracrystalline scattering. So be warned that the 2708 calculation is SLOW. Go get some coffee. Fitting of any experimental 2709 data must be resolution smeared for any meaningful fit. This makes a 2710 triple integral. Very, very slow. Go get lunch. 2711 2712 REFERENCE 2713 2714 Hideki Matsuoka et. al. *Physical Review B*, 36 (1987) 1754-1765 2715 (Original Paper) 2716 2717 Hideki Matsuoka et. al. *Physical Review B*, 41 (1990) 3854 -3856 2718 (Corrections to FCC and BCC lattice structure calculation) 2669 .. image:: img/image149.JPG 2670 2671 where *scale* is the volume fraction of spheres, *Vp* is the volume of the primary particle, *V(lattice)* is a volume 2672 correction for the crystal structure, *P(q)* is the form factor of the sphere (normalized), and *Z(q)* is the 2673 paracrystalline structure factor for a simple cubic structure. 2674 2675 Equation (16) of the 1987 reference is used to calculate *Z(q)*, using equations (13)-(15) from the 1987 paper for 2676 *Z1*\ , *Z2*\ , and *Z3*\ . 2677 2678 The lattice correction (the occupied volume of the lattice) for a simple cubic structure of particles of radius *R* 2679 and nearest neighbor separation *D* is 2680 2681 .. image:: img/image150.JPG 2682 2683 The distortion factor (one standard deviation) of the paracrystal is included in the calculation of *Z(q)* 2684 2685 .. image:: img/image151.JPG 2686 2687 where *g* is a fractional distortion based on the nearest neighbor distance. 2688 2689 The simple cubic lattice is 2690 2691 .. image:: img/image152.JPG 2692 2693 For a crystal, diffraction peaks appear at reduced *q*\ -values given by 2694 2695 .. image:: img/image153.JPG 2696 2697 where for a simple cubic lattice any *h*\ , *k*\ , *l* are allowed and none are forbidden. Thus the peak positions 2698 correspond to (just the first 5) 2699 2700 .. image:: img/image154.JPG 2701 2702 **NB: The calculation of** *Z(q)* **is a double numerical integral that must be carried out with a high density of** 2703 **points to properly capture the sharp peaks of the paracrystalline scattering.** So be warned that the calculation is 2704 SLOW. Go get some coffee. Fitting of any experimental data must be resolution smeared for any meaningful fit. This 2705 makes a triple integral. Very, very slow. Go get lunch! 2719 2706 2720 2707 ============== ======== ============= … … 2730 2717 ============== ======== ============= 2731 2718 2732 2733 2734 This example dataset is produced using 200 data points, *qmin* = 0.01 2735 -1, *qmax* = 0.1 -1 and the above default values. 2736 2737 2738 2739 *Figure. 1D plot in the linear scale using the default values (w/200 2740 data point).* 2741 2742 The 2D (Anisotropic model) is based on the reference (above) which 2743 I(q) is approximated for 1d scattering. Thus the scattering pattern 2744 for 2D may not be accurate. Note that we are not responsible for any 2745 incorrectness of the 2D model computation. 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 * * 2719 This example dataset is produced using 200 data points, *qmin* = 0.01 |Ang^-1|, *qmax* = 0.1 |Ang^-1| and the above 2720 default values. 2721 2722 .. image:: img/image155.JPG 2723 2724 *Figure. 1D plot in the linear scale using the default values (w/200 data point).* 2725 2726 The 2D (Anisotropic model) is based on the reference below where *I(q)* is approximated for 1d scattering. Thus the 2727 scattering pattern for 2D may not be accurate. Note that we are not responsible for any incorrectness of the 2D model 2728 computation. 2729 2730 .. image:: img/image156.JPG 2731 2732 .. image:: img/image157.JPG 2758 2733 2759 2734 *Figure. 2D plot using the default values (w/200X200 pixels).* 2760 2761 2762 2763 .. _FCCrystalModel:2764 2765 **2.1.35. FCCrystalModel**2766 2767 Calculates the scattering from a face-centered cubic lattice with2768 paracrystalline distortion. Thermal vibrations are considered to be2769 negligible, and the size of the paracrystal is infinitely large.2770 Paracrystalline distortion is assumed to be isotropic and2771 characterized by a Gaussian distribution.2772 2773 The returned value is scaled to units of |cm^-1|\ |sr^-1|, absolute scale.2774 2775 The scattering intensity I(q) is calculated as:2776 2777 2778 2779 where scale is the volume fraction of spheres, Vp is the volume of the2780 primary particle, V(lattice) is a volume correction for the crystal2781 structure, P(q) is the form factor of the sphere (normalized) and Z(q)2782 is the paracrystalline structure factor for a face-centered cubic2783 structure. Equation (1) of the 1990 reference is used to calculate2784 Z(q), using equations (23)-(25) from the 1987 paper for Z1, Z2, and2785 Z3.2786 2787 The lattice correction (the occupied volume of the lattice) for a2788 face-centered cubic structure of particles of radius R and nearest2789 neighbor separation D is:2790 2791 2792 2793 The distortion factor (one standard deviation) of the paracrystal is2794 included in the calculation of Z(q):2795 2796 2797 2798 where g is a fractional distortion based on the nearest neighbor2799 distance.2800 2801 The face-centered cubic lattice is:2802 2803 2804 2805 For a crystal, diffraction peaks appear at reduced q-values givn by:2806 2807 2808 2809 where for a face-centered cubic lattice h, k, l all odd or all even2810 are allowed and reflections where h, k, l are mixed odd/even are2811 forbidden. Thus the peak positions correspond to (just the first 5):2812 2813 2814 2815 NB: The calculation of Z(q) is a double numerical integral that must2816 be carried out with a high density of points to properly capture the2817 sharp peaks of the paracrystalline scattering. So be warned that the2818 calculation is SLOW. Go get some coffee. Fitting of any experimental2819 data must be resolution smeared for any meaningful fit. This makes a2820 triple integral. Very, very slow. Go get lunch.2821 2735 2822 2736 REFERENCE … … 2827 2741 Hideki Matsuoka et. al. *Physical Review B*, 41 (1990) 3854 -3856 2828 2742 (Corrections to FCC and BCC lattice structure calculation) 2743 2744 2745 2746 .. _FCCrystalModel: 2747 2748 **2.1.35. FCCrystalModel** 2749 2750 Calculates the scattering from a **face-centered cubic lattice** with paracrystalline distortion. Thermal vibrations 2751 are considered to be negligible, and the size of the paracrystal is infinitely large. Paracrystalline distortion is 2752 assumed to be isotropic and characterized by a Gaussian distribution. 2753 2754 The returned value is scaled to units of |cm^-1|\ |sr^-1|, absolute scale. 2755 2756 *2.1.35.1. Definition* 2757 2758 The scattering intensity *I(q)* is calculated as 2759 2760 .. image:: img/image158.JPG 2761 2762 where *scale* is the volume fraction of spheres, *Vp* is the volume of the primary particle, *V(lattice)* is a volume 2763 correction for the crystal structure, *P(q)* is the form factor of the sphere (normalized), and *Z(q)* is the 2764 paracrystalline structure factor for a face-centered cubic structure. 2765 2766 Equation (1) of the 1990 reference is used to calculate *Z(q)*, using equations (23)-(25) from the 1987 paper for 2767 *Z1*\ , *Z2*\ , and *Z3*\ . 2768 2769 The lattice correction (the occupied volume of the lattice) for a face-centered cubic structure of particles of radius 2770 *R* and nearest neighbor separation *D* is 2771 2772 .. image:: img/image159.JPG 2773 2774 The distortion factor (one standard deviation) of the paracrystal is included in the calculation of *Z(q)* 2775 2776 .. image:: img/image160.JPG 2777 2778 where *g* is a fractional distortion based on the nearest neighbor distance. 2779 2780 The face-centered cubic lattice is 2781 2782 .. image:: img/image161.JPG 2783 2784 For a crystal, diffraction peaks appear at reduced q-values given by 2785 2786 .. image:: img/image162.JPG 2787 2788 where for a face-centered cubic lattice *h*\ , *k*\ , *l* all odd or all even are allowed and reflections where 2789 *h*\ , *k*\ , *l* are mixed odd/even are forbidden. Thus the peak positions correspond to (just the first 5) 2790 2791 .. image:: img/image163.JPG 2792 2793 **NB: The calculation of** *Z(q)* **is a double numerical integral that must be carried out with a high density of** 2794 **points to properly capture the sharp peaks of the paracrystalline scattering.** So be warned that the calculation is 2795 SLOW. Go get some coffee. Fitting of any experimental data must be resolution smeared for any meaningful fit. This 2796 makes a triple integral. Very, very slow. Go get lunch! 2829 2797 2830 2798 ============== ======== ============= … … 2840 2808 ============== ======== ============= 2841 2809 2842 This example dataset is produced using 200 data points, *qmin* = 0.01 2843 -1, *qmax* = 0.1 -1 and the above default values. 2844 2845 2846 2847 *Figure. 1D plot in the linear scale using the default values (w/200 2848 data point).* 2849 2850 The 2D (Anisotropic model) is based on the reference (above) in which 2851 I(q) is approximated for 1d scattering. Thus the scattering pattern 2852 for 2D may not be accurate. Note that we are not responsible for any 2853 incorrectness of the 2D model computation. 2854 2810 This example dataset is produced using 200 data points, *qmin* = 0.01 |Ang^-1|, *qmax* = 0.1 |Ang^-1| and the above 2811 default values. 2812 2813 .. image:: img/image164.JPG 2814 2815 *Figure. 1D plot in the linear scale using the default values (w/200 data point).* 2816 2817 The 2D (Anisotropic model) is based on the reference below where *I(q)* is approximated for 1d scattering. Thus the 2818 scattering pattern for 2D may not be accurate. Note that we are not responsible for any incorrectness of the 2D model 2819 computation. 2820 2821 .. image:: img/image165.GIF 2822 2823 .. image:: img/image166.JPG 2855 2824 2856 2825 *Figure. 2D plot using the default values (w/200X200 pixels).* 2857 2858 2859 2860 .. _BCCrystalModel:2861 2862 **2.1.36. BCCrystalModel**2863 2864 Calculates the scattering from a body-centered cubic lattice with2865 paracrystalline distortion. Thermal vibrations are considered to be2866 negligible, and the size of the paracrystal is infinitely large.2867 Paracrystalline distortion is assumed to be isotropic and2868 characterized by a Gaussian distribution.The returned value is scaled2869 to units of |cm^-1|\ |sr^-1|, absolute scale.2870 2871 The scattering intensity I(q) is calculated as:2872 2873 2874 2875 where scale is the volume fraction of spheres, Vp is the volume of the2876 primary particle, V(lattice) is a volume correction for the crystal2877 structure, P(q) is the form factor of the sphere (normalized) and Z(q)2878 is the paracrystalline structure factor for a body-centered cubic2879 structure. Equation (1) of the 1990 reference is used to calculate2880 Z(q), using equations (29)-(31) from the 1987 paper for Z1, Z2, and2881 Z3.2882 2883 The lattice correction (the occupied volume of the lattice) for a2884 body-centered cubic structure of particles of radius R and nearest2885 neighbor separation D is:2886 2887 2888 2889 The distortion factor (one standard deviation) of the paracrystal is2890 included in the calculation of Z(q):2891 2892 2893 2894 where g is a fractional distortion based on the nearest neighbor2895 distance.2896 2897 The body-centered cubic lattice is:2898 2899 2900 2901 For a crystal, diffraction peaks appear at reduced q-values givn by:2902 2903 2904 2905 where for a body-centered cubic lattice, only reflections where2906 (h+k+l) = even are allowed and reflections where (h+k+l) = odd are2907 forbidden. Thus the peak positions correspond to (just the first 5):2908 2909 2910 2911 NB: The calculation of Z(q) is a double numerical integral that must2912 be carried out with a high density of points to properly capture the2913 sharp peaks of the paracrystalline scattering. So be warned that the2914 calculation is SLOW. Go get some coffee. Fitting of any experimental2915 data must be resolution smeared for any meaningful fit. This makes a2916 triple integral. Very, very slow. Go get lunch.2917 2826 2918 2827 REFERENCE … … 2923 2832 Hideki Matsuoka et. al. *Physical Review B*, 41 (1990) 3854 -3856 2924 2833 (Corrections to FCC and BCC lattice structure calculation) 2834 2835 2836 2837 .. _BCCrystalModel: 2838 2839 **2.1.36. BCCrystalModel** 2840 2841 Calculates the scattering from a **body-centered cubic lattice** with paracrystalline distortion. Thermal vibrations 2842 are considered to be negligible, and the size of the paracrystal is infinitely large. Paracrystalline distortion is 2843 assumed to be isotropic and characterized by a Gaussian distribution. 2844 2845 The returned value is scaled to units of |cm^-1|\ |sr^-1|, absolute scale. 2846 2847 *2.1.36.1. Definition** 2848 2849 The scattering intensity *I(q)* is calculated as 2850 2851 .. image:: img/image167.JPG 2852 2853 where *scale* is the volume fraction of spheres, *Vp* is the volume of the primary particle, *V(lattice)* is a volume 2854 correction for the crystal structure, *P(q)* is the form factor of the sphere (normalized), and *Z(q)* is the 2855 paracrystalline structure factor for a body-centered cubic structure. 2856 2857 Equation (1) of the 1990 reference is used to calculate *Z(q)*, using equations (29)-(31) from the 1987 paper for 2858 *Z1*\ , *Z2*\ , and *Z3*\ . 2859 2860 The lattice correction (the occupied volume of the lattice) for a body-centered cubic structure of particles of radius 2861 *R* and nearest neighbor separation *D* is 2862 2863 .. image:: img/image159.JPG 2864 2865 The distortion factor (one standard deviation) of the paracrystal is included in the calculation of *Z(q)* 2866 2867 .. image:: img/image160.JPG 2868 2869 where *g* is a fractional distortion based on the nearest neighbor distance. 2870 2871 The body-centered cubic lattice is 2872 2873 .. image:: img/image168.JPG 2874 2875 For a crystal, diffraction peaks appear at reduced q-values given by 2876 2877 .. image:: img/image162.JPG 2878 2879 where for a body-centered cubic lattice, only reflections where (\ *h* + *k* + *l*\ ) = even are allowed and 2880 reflections where (\ *h* + *k* + *l*\ ) = odd are forbidden. Thus the peak positions correspond to (just the first 5) 2881 2882 .. image:: img/image169.JPG 2883 2884 **NB: The calculation of** *Z(q)* **is a double numerical integral that must be carried out with a high density of** 2885 **points to properly capture the sharp peaks of the paracrystalline scattering.** So be warned that the calculation is 2886 SLOW. Go get some coffee. Fitting of any experimental data must be resolution smeared for any meaningful fit. This 2887 makes a triple integral. Very, very slow. Go get lunch! 2925 2888 2926 2889 ============== ======== ============= … … 2936 2899 ============== ======== ============= 2937 2900 2938 2939 2940 This example dataset is produced using 200 data points, *qmin* = 0.001 2941 -1, *qmax* = 0.1 -1 and the above default values. 2942 2943 2944 2945 *Figure. 1D plot in the linear scale using the default values (w/200 2946 data point).* 2947 2948 The 2D (Anisotropic model) is based on the reference (1987) in which 2949 I(q) is approximated for 1d scattering. Thus the scattering pattern 2950 for 2D may not be accurate. Note that we are not responsible for any 2951 incorrectness of the 2D model computation. 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2901 This example dataset is produced using 200 data points, *qmin* = 0.001 |Ang^-1|, *qmax* = 0.1 |Ang^-1| and the above 2902 default values. 2903 2904 .. image:: img/image170.JPG 2905 2906 *Figure. 1D plot in the linear scale using the default values (w/200 data point).* 2907 2908 The 2D (Anisotropic model) is based on the reference below where *I(q)* is approximated for 1d scattering. Thus the 2909 scattering pattern for 2D may not be accurate. Note that we are not responsible for any incorrectness of the 2D model 2910 computation. 2911 2912 .. image:: img/image165.GIF 2913 2914 .. image:: img/image171.JPG 2964 2915 2965 2916 *Figure. 2D plot using the default values (w/200X200 pixels).* 2917 2918 REFERENCE 2919 2920 Hideki Matsuoka et. al. *Physical Review B*, 36 (1987) 1754-1765 2921 (Original Paper) 2922 2923 Hideki Matsuoka et. al. *Physical Review B*, 41 (1990) 3854 -3856 2924 (Corrections to FCC and BCC lattice structure calculation) 2966 2925 2967 2926
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