Unified Gas-Adsorbate Layer UGAL Model

To formulate the UGAL model let us introduce the distribution function of gEiseous particles gdb, r, t) normalized by (6.1.12). The description of the adsorbate kinetics is reduced then to solving a Cauchy problem 

Here d,e is the classic Poisson bracket, e is the total energy with the accoimt of self-consistent field, l(p) is the collision integral of Boltzmann-Landau type, the kernel r(p,pf) and the collision cross-section in l( ) are expressed through the amplitude of binary quasiparticle scattering. 

In the kinetics of non-ideal media the rel lxation operator J(gc) is often split into two parts, describing strong and weeik interactions 

Operator F( c), responsible for the weak interactions, has the Fokker-Planck form, while strong interactions operator N(yc) is approximated in different ways, depending on the type and mechanism of the transition. The latter operator is responsible for large momentum transfers and significant changes of physical and chemical characteristics of the molecule. For example, in case of inelastic interactions and chemical reactions one can use representation (6.1.18) with the only difference, that in the UGAL model there stands a unified distribution function c(6, r,t). For large momentum tremsfer the model of hard spheres is used. 

If weak intereictions lead only to small momentum increments one can approximate the operator f(gc) as 

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