On the spline approximation of low-temperature calorimetry data

An algorithm for the spline approximation of heat capacity taking into account the Debye or Tarasov asymptotes in extrapolation from the first experimental temperature to 0 K was developed. The possibility of applying other boundary conditions that do not contradict the modern concepts of the behavior of heat capacity as a function of temperature is considered. A procedure for selecting the smoothing parameter based on a priori specifying the number of inflection points in the smoothing dependence is suggested. Possibilities for estimating the accuracy of approximation with the use of the orthogonal functions are discussed.