The program requires one input file, called PARC.DAT, in which 
the values for the following parameters must appear,
1. the name of the output file;
2. the metal nuclear spin I;
3. the gamma_I value of the observed nucleus in rad (s T)^{-1};
4. the electron spin S;
5. the choice of T_1^{-1} or T_2^{-1} calculation to be performed;
6. the range of magnetic fields (or proton Larmor frequencies);
7. the number of points in the curve that have to be generated;
8. the number of profiles at different temperatures;
9. the values of the temperature
10.the parameters relative to the metal:
a. tau_e (in s) or, as an alternative,
a1. Delta_t (in cm^{-1}),
a2. tau_v (in s);
b. the axial component of the zero field splitting D (in cm^{-1});
c. the rhombic component of the zero field splitting E (in cm^{-1});
d. the a_4 constant (in cm^{-1});
e. the g_{xx} component of the g tensor in the molecular frame;
f. the g_{yy} component of the g tensor in the molecular frame;
g. the g_{zz} component of the g tensor in the molecular frame;
h. the A_{xx} component of the hyperfine coupling tensor (in cm^{-1});
i. the A_{yy} component of the hyperfine coupling tensor (in cm^{-1});
l. the A_{zz} component of the hyperfine coupling tensor (in cm^{-1});
m. the distance d of closest approach for the diffusion relaxation (in A);
n. the diffusion coefficient D (in cm^2 s^{-1});
o. the concentration (in M) ;
p. the number of inequivalent paramagnetic sites. This number
indicates the number of times that the following parameters have to be
repeated (one set for each site):
I. the nuclear chemical exchange time tau_m (in s);
II. the number of interacting nuclei;
III. the distance r between the paramagnetic center and the nucleus (in A);
IV. the constant of contact interaction a/h (in MHz);
V. the angle theta between the z-molecular axis in which the tensors D, g 
and/or A are diagonal and the I-S vector (in degree);
VI. the angle phi between the projection of the I-S vector on the plane of
the molecule perpendicular to the z-axis and the x-molecular axis
(in degree).
 
In the output file the values
of frequency (in MHz) and proton relaxation rate (in s^{-1}), for a 
plot of the curve, are stored.