function [ Theta ] = ThetaCO( T, p )
%
%[ Theta ] = ThetaCO( T, p )
%
%  This function calculated the coverage fraction 
%  Theta of CO on a heterogeneous Pt surface.
%  T is the temperature in kelvin, p is the 
%  CO partial pressure in pascal.
%
%  Should not be used outside of the range of 
%  Theta between 0.01 and 0.9.
%
%  Guinn et al., Surface Science 393 (1997) 47-63

th = 0.0573E-3 * 8.314 * T / ( 1 - 0.00133 * T ) ;
K  = 6.57E-7 * exp( 89.8E3 / 8.314 / T ) ;

Theta = ( K * p )^th / ( 1 + ( K * p )^th ) ;