EPRLL program

The EPRLL programs also allow for non-Brownian rotational diffusion, which implies a discrete, step motion of the spin probe. Two limiting models are available (i) jump diffusion, and (2) approximate free diffusion. In currently available implementations of the SEE fine shape calculation, non-Brownian models may not be used with an orienting potential, and only with the assumption of an axially symmetric diffusion tensor. For these reasons, and since Brownian motion is usually an... 

The dynamic parameters for the EPRLL program are summarized and defined in Table 3. 

Each basis function in the EPRLL program is specified by five quantum numbers L, K, M, pi, Qi, with L, K, and M specifying the generalized spherical harmonic function, and the transition indices pi and ft specifying the spin functions. Note here that pi and ft refer only to nuclear spin states. In the general formulation of the SLE, it would also be necessary to include the indices ps and for the electronic spin states however, the EPRLL programs make use of the high-field approximation, which implicitly restricts the calculation to the ps = 1. s = 0 subspace. The basis set indices and the physical quantities they represent are summarized in Table 5. 

TABLE 6. Control Parameters Used in EPRLL Programs... 

The control parameters used in the EPRLL programs are sununarized and defined in Table 6. 

PC.NEW A new addition that contains a version of the EPRLL programs suitable for running on a pc with Windows 95. Only the source files that have been changed from the EPRLL directory are included, plus the executables. See the README file on that directory. 

An alternative form for specifying tensor principal values that is sometimes used in the EPRLL-family programs is the spherical representation. In terms of the Cartesian components of a tensor M, namely, M, My, and M, its spherical components are defined as... 

Table 1 summarizes the magnetic parameter names that are used in the EPRLL family programs to specify the spin Hamiltonian for a electron spin radical with a single significant nucleus, such as a nitroxide spin label. 

The physical interpretation of the residence time for a given axis depends on the specific model used. In jump diffusion, the molecule remains stationary for an average time T after which it jumps to a new orientation, specified by an angle of rotation about the specified axis. The root-mean-square reorientation angle (in rad) is given by the formula = (0 ) = R-t, where i specifies the axis perpendicular or parallel to Zr. In the approximate free diffusion model, the molecule rotates freely about axis i with a rotational rate / , but instantaneously reorients at an average interval x, after which it continues its free rotation. Like all of the other dynamic parameters in the EPRLL family programs, the non-Brownian residence time products are specified on the log 10 scale. 

The EPRLL-family programs include additional restrictions on the terms in Eq. 2. The summation is restricted to even values of L and K that are < 4. Thus, there are... 

For any of the basic EPRLL-family programs, it is necessary to specify the range of basis set indices that will be used to construct the SLE matrix equation. This is done via the five truncation parameters, Lon , and which specify the... 

EPRLL Contains the basic simulation program for CW spectrum calculation including the program EPRBL used to determine the tmncated basis sets. 

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