Plotting Power spectral density of Simple Rossler Attractor

I have been trying to plot a figure of the power spectrum for Rossler system which I found in a paper entitled 'Power spectra and mixing properties of strange attractors' by Doyne Farmer. I wrote a MATLAB code to generate the figure but not getting the plot exactly what is in that paper. Here is my code-

       close all;clc;
        global  a b c
         a=0.2;
         b=0.4;
         c=5.7;
     ts=0:.01:4000;
     z0=[1 0 1]; 
     opt=odeset('RelTol',10e-12);
     [t,z]= ode45('System', ts, z0,opt);
     Fs = 1000;   
     x=z(:,1);
     nfft = 2^nextpow2(length(x));
     Pxx = abs(fft(x,nfft)).^2/length(x)/Fs;
     Hpsd = dspdata.psd(Pxx(1:length(Pxx)/2),'Fs',Fs/10); 
     figure()
     plot(Hpsd)

subject to the function

    function zdot=System(t,z) 

      global a b c

   zdot=[ -(z(2)+z(3));
           z(1)+a*z(2);
           b+z(1)*z(3)-c*z(3)];

I, hereby, attach the paper also for your perusal. Please solve the error in my code.