Specific forces

While atom typits are tied to a specific force fields, it is easy to modify each force field s atom types the functional form cannot be modified but atom types can. The next section describes how atom types are defined. 

Atom types are defined in the file chem.rul. The atom types for each of the force fields are listed in the files pointed to by the AtomTypeMass entries associated with the specific force fields in the Registry or the chem.ini file. They are usually named typ.txt or typ.dbf, depending on whether text or dBASE format is used. For the AMBER force field, all variations use the same type file, defined in the [Amber] section of the Registry or the chem.ini file. It is usually called ambertyp.txt, if a text format file is used, indicated by FileFormat=Text or ambertyp.dbf, if a dBASE III format file is used, indicated by FileFormat=dbf. 

Frequency is defined as the number of repetitions of a specific forcing function or vibration component over a specific unit of time. Take for example a four-spoke wheel with an accelerometer attached. Every time the shaft completes one rotation, each of the four spokes passes the accelerometer once, which is referred to as four cycles per revolution. Therefore, if the shaft rotates at 100 rpm, the frequency of the spokes passing the accelerometer is 400 cycles per minute (cpm). In addition to cpm, frequency is... 

In general, three basic kinds of sorption mechanisms for trace elements in geologic aqueous systems can be distinguished (56). Due to non-specific forces of attraction between sorbent and the solute, a physical adsorption may occur. This sorption mechanism results in the binding of species from the solution in several consecutive layers on exposed solid surfaces. This would be a rapid non-selec-tive and reversible process, fairly independent of nuclide concentration and only little dependent on ion exchange capacity of the solid. 

The subscript e means that the second derivatives are taken for internal parameters of the known or assumed molecular geometry.) It then follows that, in principle, to every molecule a F-matrix is assigned with molecule-specific force constants Fd.Transferability can only be expected for molecules which contain qualitatively and quantitatively very similar internal coordinates For instance, a force field which reproduces very well frequencies of n-al-kanes (from which it was derived) gives significantly worse results for branched alkanes... 

The previous models were developed for Brownian particles, i.e. particles that are smaller than about 1 pm. Since most times particles that are industrially codeposited are larger than this, Fransaer developed a model for the codeposition of non-Brownian particles [38, 50], This model is based on a trajectory analysis of particles, including convective mass transport, geometrical interception, and migration under specific forces, coupled to a surface immobilization reaction. The codeposition process was separated in two sub-processes the reduction of metal ions and the concurrent deposition of particles. The rate of metal deposition was obtained from the diffusion... 

Suppose the inequality constraints on ethylene and propylene production were changed to equality constraints (ethylene = 50,000 propylene = 20,000). The optimal solution for these conditions is shown as case 2 in Table E14.1B. This specification forces the use of DNG as well as ethane. 

We consider that the application of standard force fields to homogeneous catalysis continues nowadays to be useful for preliminary qualitative descriptions, but that for a more quantitative description within the MM method one must necessarily go to the design of a specific force field for a... 

This corresponds to the solution for the unforced or undisturbed system. Now we must find the particular solutions for some specific forcing functions m(,). Then the total solution will be the sum of the complementary and particular solutions. 

Wc can determine the dynamics and the steadystate characteristics of the system without having to pick any specific forcing function. 

The values of — AH for benzene are in the range 10-12 kcal/mole,15,19-20 being intermediate between values attributed to pure dispersion forces for saturated hydrocarbons and those in which more specific forces are involved. Furthermore, Ron and coworkers calculated the entropies of adsorption for benzene and concluded that the mobile gas model of adsorption was applicable, and Whalen18 found no simple relationship between the hydroxy site content and benzene adsorption. These results confirm the conclusions reached from the infrared data that benzene adsorption is essentially due to dispersion forces which should be greater than with saturated compounds, and that no hydrogen bonding is involved. 

Berthelot s characteristic product 2 BIOS—B106 absolute temp of expln 2 BIOS specific force 2 BIOS... 

The following table gives the characteristic product, specific force, Qe, V0 and T values for some explosives(Ref 3.P 152)... 

The forces involved in the adsorption of gases and vapours by solids may be non-specific (van der Waals) forces, similar to the forces involved in liquefaction, or stronger specific forces, such as those which are operative in the formation of chemical bonds. The former are responsible for physical adsorption and the latter for chemisorption. 

The differential quantity of work done by a specific force is defined as the product of the force and the differential change of the conjugate coordinate. The differential quantity of work done by the system on the surroundings is expressed as... 

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