Thermal corrections, computed internal

Thermal corrections to the computed internal energy are necessary to obtain energies at temperatures which are directly comparable to experimental conditions [27]. The thermal corrections to the internal energy are determined by contributions... 

The internal energy at a specific temperature is then determined by the sum of the internal thermal energy correction term and the computed electronic energy. Take 298 K, as an example. 

The criterion for improvement used below is the internal energy of the model. In choosing a particular criterion function one must examine both its validity and the accuracy with which it can be computed. Strictly speaking, the conformational free energy and not the conformational energy is a minimum for the experimentally observed conformation. However, for a crystal or the interior of a folded macromolecule the use of the energy is not a bad approximation if a correction for expansion due to vibrational (thermal) motion is applied. 

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