Debeye' s Formula plotting

Good day. I hope someone can help with this one. I'm planning to evaluate Debeye's Formula as seen on image below. What is the most applicable method of numerical integration method I can use? How can I apply this numerical integration method. Thank you and have a nice day

[per isakson]

See integral Numerical integration

[Darwin Tuazon]

How can I apply the numerical integration in my problem? I'm new in MATLAB. Can you provide me details on how can I apply the numerical integration from the link you have sent. Thank you