Unit of the eigenvalues of the PCA

[Former user]

Hi,

I am new to the topic of PCA and now I have a question regarding the eigenvalues. If I perform a PCA on a trajectory, which unit do the eigenvectors have? Angstrom? Or nanometers?

Thanks in advance for helping me!

[Xinqiu Yao]

Eigenvectors are normalized and so there is no unit. For eigenvalues, it is 'angstrom square', because they represent the variance along each PC.