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Non-linear least squares fit of specific heat data within the Schotte–Schotte model using web page

2019; Elsevier BV; Volume: 240; Linguagem: Inglês

10.1016/j.cpc.2019.02.010

1879-2944

Jerzy Goraus,

Advanced Condensed Matter Physics

Specific heat of rare-earth based materials at low temperatures can often be described by the Schotte–Schotte model for Kondo impurity. For several decades thousands of papers have been published which were devoted to physics of rare-earth based compounds and often presented specific heat measurements for Kondo systems. The Schotte–Schotte model for Kondo impurity in a magnetic field requires evaluation of trigamma function for complex argument values. Typical graphing software for general use does not provide such capability. Therefore, very few papers related to Kondo effect in rare-earth based compounds provided analysis within that model. In this report we present a web page which fits specific heat data with a sum of electronic, lattice and Schotte–Schotte terms. The interface is written in Javascript, whereas back-end fitting engine is written in C and compiled to Javascript asm.js code using Emscripten compiler. Program title: SCHfit Program Files doi: http://dx.doi.org/10.17632/xyzdj2fdvs.1. Licensing provisions: MIT Programming language: Javascript/C/HTML Nature of problem: Typical graphing software does not allow non-linear least squares fit of models involving special functions like trigamma function. Moreover, it does not allow evaluation of such models for a complex argument. Solution method: We provide a standalone web page, which does not require running a web server (it can run from a web browser) that fits a particular model of specific heat data for rare-earth based materials (the Schotte–Schotte model [1]). Additional comments: Web page is hosted at http://www.jerzy.goraus.us.edu.pl/schfit.html. Source files are provided at http://www.jerzy.goraus.us.edu.pl/schfit.zip. The interface is implemented in HTML/Javascript, whereas the fitting back-end is in the form of asm.js code compiled from C source. The web page can be run locally in a browser, even without internet connection. We also provide a simple floating point benchmark of the machine which runs the web browser at http://www.jerzy.goraus.us.edu.pl/mf.html. [1] K. D. Schotte, U. Schotte, Phys. Lett. 55 (1975) 38–40