release_v0.94release_v0.95
Last change
on this file since f837f0b was
2c74c11,
checked in by Paul Kienzle <pkienzle@…>, 8 years ago
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implicit Iqxy; fix divide by 0 for q=0
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-
Property mode set to
100644
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File size:
1.5 KB
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1 | double Iq(double q, |
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2 | double volfraction, |
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3 | double radius, |
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4 | double fractal_dim, |
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5 | double cor_length, |
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6 | double sld_block, |
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7 | double sld_solvent); |
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8 | |
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9 | double Iq(double q, |
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10 | double volfraction, |
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11 | double radius, |
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12 | double fractal_dim, |
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13 | double cor_length, |
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14 | double sld_block, |
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15 | double sld_solvent) |
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16 | { |
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17 | double qr,r0,Df,corr,phi,sldp,sldm; |
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18 | double pq,sq,inten; |
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19 | |
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20 | // Actively check the argument - needed for mass fractal - is it needie |
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21 | //here? |
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22 | if (fractal_dim <= 0.0){ |
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23 | return 0.0; |
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24 | } |
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25 | |
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26 | phi = volfraction; // volume fraction of building block spheres... |
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27 | r0 = radius; // radius of building block |
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28 | Df = fractal_dim; // fractal dimension |
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29 | corr = cor_length; // correlation length of fractal-like aggregates |
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30 | sldp = sld_block; // SLD of building block |
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31 | sldm = sld_solvent; // SLD of matrix or solution |
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32 | |
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33 | qr=q*r0; |
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34 | |
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35 | //calculate P(q) for the spherical subunits |
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36 | pq = phi*M_4PI_3*r0*r0*r0*(sldp-sldm)*(sldp-sldm)*sph_j1c(qr)*sph_j1c(qr); |
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37 | |
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38 | //calculate S(q) |
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39 | sq = Df*sas_gamma(Df-1.0)*sin((Df-1.0)*atan(q*corr)); |
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40 | sq /= pow(qr,Df) * pow((1.0 + 1.0/(q*corr)/(q*corr)),((Df-1.0)/2.0)); |
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41 | sq += 1.0; |
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42 | |
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43 | //combine, scale to units cm-1 sr-1 (assuming data on absolute scale) |
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44 | //and return |
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45 | inten = pq*sq; |
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46 | // convert I(1/A) to (1/cm) |
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47 | inten *= 1.0e8; |
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48 | //convert rho^2 in 10^-6 1/A to 1/A |
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49 | inten *= 1.0e-12; |
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50 | |
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51 | |
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52 | return(inten); |
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53 | } |
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54 | |
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