Xray::Scattering(3pm)

💖 Xray::Scattering 💖

okay bestie, so this is the manual page for Xray::Scattering — it's a Perl module (that's the (3pm) situation, we love a lil library moment) and it ships you all the X-ray scattering data for the elements. User contributed Perl documentation, and it ate. 🫶

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✨ NAME ✨

Xray::Scattering — X-ray scattering data for the elements 🌈

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🌸 SYNOPSIS 🌸

use Xray::Scattering;
Xray::Scattering->load('CroMann');
$fnot = Xray::Scattering->get_f($symb, $d);

Xray::Scattering->load('WaasKirt');
$fnot = Xray::Scattering->get_f($symb, $d);

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🦋 DESCRIPTION 🦋

So this module gives you access to X-ray scattering data for atoms and ions. It's designed to be a transparent interface to scattering data from a bunch of different sources — like, you don't gotta care where the numbers came from, you just ask and it delivers. ✨

Currently the only data sources are:

• the Cromer-Mann tables from the International Tables of Crystallography 📖
• the 1995 Waasmaier-Kirfel tables 🗂️

More resources can be added easily, so this is very much giving expandable, main character energy.

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👑 METHODS 👑

available

This one returns a list of the data resources that are available to this module. Right now it hands you back an array consisting of these strings:

Cromer-Mann  Waasmaier-Kirfel  None

The first two are functional interfaces to those databases — actual working vibes. The third, None, is a fallback subclass which returns default values for all methods. It's the friend who shows up and contributes nothing but is still invited. 💀

get_valence

This returns the element/valence symbol in the proper form for use with the other methods. $elem is a two-letter atomic symbol, and $valence is the valence of the ion. And $valence can be an integer, a float, a dot, or the string "va" — versatile, we stan. 💅

$symbol = Xray::Scattering->get_valence($elem, $valence)

Unless the valence is a dot or the string "va", the nearest integer to $valence is used with the element symbol to construct the element/valence symbol. For example, $symbol eq "Cu2+" if $elem eq "Cu" and $valence == 2. Simple as that, no cap. 🎀

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🧚 SUBCLASS METHODS 🧚

All the available subclasses corresponding to the data resources provide their own versions of the following methods. Same function names, different table behind the curtain, iykyk.

get_f

This function calculates the Thomson scattering for a given symbol and d-spacing. The Thomson scattering depends only on the momentum transfer. The d-spacing of the scattering planes is a closely related quantity and is easily calculated from the crystal structure — see Xtal.pm for that whole situation. 🔥

$symb = "Ce3+";
$fnot = Xray::Scattering->get_f($symb, $d);

Here's the tea on the edge cases, bestie, listen up:

• If the symbol cannot be found in the table, get_f returns 0.
• It also returns 0 when $symbol consists of whitespace or is "null" or "nu".
• If $symbol is a number or the name of an element, then it assumes you want the Thomson scattering for the neutral element.
• The absolute value of $d_spacing is used by this function.

The None subclass always returns 0. Iconic in its commitment to nothing. 💀

If you ask for a valence state that is not in the table but for an element whose 0+ state is in the table, this method returns the scattering factor for the 0 valent atom. It's got your back like that. 🫶

get_coefficients

This returns the 9 (Cromer-Mann) or 11 (Waasmaier-Kirfel) element list containing the coefficients for the given symbol. Nine or eleven, depending on which table you're living in. 🌟

@coefs = Xray::Scattering->get_coefficients($symb)

See the documents for the subclasses for the order of the coefficients — the ordering matters, don't just vibe-check it.

The None subclass always returns a list of 11 zeros. Eleven beautiful zeros. 🎀

If you ask for a valence state that is not in the table but for an element whose 0+ state is in the table, this method returns the coefficients for the 0 valent atom. Same energy as get_f, consistent queen. 👑

has

This is a test of whether a given symbol is tabulated in the selected data resource table. It returns the symbol itself if it's found in the table, or 0 if it's not in the table. Basically "do I know her?" 💅

$symb = "Ce3+";
$has = Xray::Scattering->has($symb);

The None subclass returns the symbol itself. No matter what. Chaos, but consistent chaos. 🦋

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🌟 AUTHOR 🌟

Bruce Ravel, bravel AT bnl DOT gov

http://cars9.uchicago.edu/~ravel/software/exafs/

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💜 LICENCE AND COPYRIGHT 💜

Copyright (c) 2006-2008 Bruce Ravel (bravel AT bnl DOT gov). All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic. Free software, we love to see it. 🎉

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Fr fr, no promises, use at your own risk bestie. 😭

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and that's the whole page!! this doc came from perl v5.34.0 and it's dated 2022-06-28 — so yes, she's a lil vintage but she still serves. mwah, go scatter some X-rays 💅✨