Question regarding compute and plot DC-centered Power Spectral Density for Time Autocoorelation function , Rx(tau)=exp(-tau/T) , I have 3 different T values ( 1 , 5 , 10 ) , code below but it is not showing PSD as expected

% script plotting Autocorrelation function for different T values
% Plotting Power Spectral Density 
% Rx(tau)=exp(-tau/T)Rx(tau)=exp(-tau/T)
clc
clear
m=5;
tau=-10:0.01:10;
L=length(tau);
T=[1 5 10];
for j=1:3
xt(:,j)=exp(-abs(tau)/T(j));
[Pxx(:,j),f(:,j)] = periodogram(xt(:,j));
figure(1)
subplot(3,1,j)
plot(tau,xt(:,j))
grid on
grid minor
xlabel('Tau in Seconds')
ylabel('R_x(Tau)')
figure(2)
subplot(3,1,j)
plot(f,10*log10(Pxx(:,j)))
grid on
grid minor
xlabel('Hz')
ylabel('dB')
end

How to compute and plot DC-centered Power Spectral DensityDC-centered Power Spectral Density for Time Autocoorelation function , Rx(tau)=exp(-tau/T) Time Autocoorelation function , Rx(tau)=exp(-tau/T) , I have 3 different T values ( 1 , 5 , 10 ) , code below but it is not showing PSD as expected

[KALYAN ACHARJYA]

but it is not showing PSD as expected

What is your expectation?

[Mohamad]

I need to see in the plot , as i change T value , then PSD becomes wide in frequency domain or narrow according to the value of T