Fragment internal structure

In general, for each acid HA, the HA-(H20) -Wm model reaction system (MRS) comprises a HA (H20) core reaction system (CRS), described quantum chemically, embedded in a cluster of Wm classical, polarizable waters of fixed internal structure (effective fragment potentials, EFPs) [27]. The CRS is treated at the Hartree-Fock (HF) level of theory, with the SBK [28] effective core potential basis set complemented by appropriate polarization and diffused functions. The W-waters not only provide solvation at a low computational cost they also prevent the unwanted collapse of the CRS towards structures typical of small gas phase clusters by enforcing natural constraints representative of the H-bonded network of a surface environment. In particular, the structure of the Wm cluster equilibrates to the CRS structure along the whole reaction path, without any constraints on its shape other than those resulting from the fixed internal structure of the W-waters. 

After hydration, a rise in temperature causes disruption of internal structure, for example crystallites in starch or folded structure in proteins. The extent to which this is achieved is determined primarily by a specific cooperative melting event, whose temperature is dependent upon moisture content and applied pressure. If these critical conditions are reached by any part of the flow stream, then shear can cause further fragmentation of both starch granules and the polymers released from them, whereas for proteins or their dissociated subunits, molecular weights remain largely imchanged. A polymer continuous melt is formed in both cases. 

Here A and B are heavy molecular fragments and their internal structure is not specified in detail now. The centers of gravity of the B, A and H particles lie on the same straight line. The proton coordinate (s) is measured from the center of gravity ( ) of the whole system (9.1). The distance between the terminal atoms (rather than between the centers of gravity of fragments B and A) is usually taken as the coordinate R. Typical values of the reduced masses (m and M) and characteristic frequencies (v g and v ) corresponding to the s and R coordinates are m 1 and M > 10 a.u. > 1000 and Vg < 200 cnr. ... 

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