function  sr_rate_O_O2
% Convergence of the Simpson's rule integration for the O-O2 dissociation
clc
format long e
temp=6000; kt=0.8617e-04*temp; yzero=14.5/kt; zmax=20;
for n=20:20:400
z=linspace(0,zmax,n+1); [sig]=sigma_O_O2((z+yzero)*kt);
f1=1e12*z.*exp(-z).*sig;
f2=1e12*exp(-z).*sig;
rate1=(z(2)-z(1))/3*(f1(1)+4*sum(f1(2:2:n))+2*sum(f1(3:2:n-1))+f1(n+1));
rate2=(z(2)-z(1))/3*(f2(1)+4*sum(f2(2:2:n))+2*sum(f2(3:2:n-1))+f2(n+1));
rate=exp(-yzero)*rate1+yzero*exp(-yzero)*rate2;
fprintf('%i %12.6f\n',n,rate)
end
function [sig]=sigma_O_O2(e)
n=length(e);
for i=1:n
sig(i)=4.51*(e(i)-14.5)^1.03/(0.21+e(i)^1.31);
end