A bit of confusion about EOS

I’m looking for some information about the EOS of materials.
And I am also grateful to MP for providing so many calculations.
But here is a problem when I looked at the results.
The pics of EOS of some materials shows that the volume is negative and energy is positive.
I think this is confuse for me and why?

hope for answer

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Thanks @zzyfor2019, I’ll look into it – it could be a plotting error.

Thanks again for letting us know about this, I think it was a simple mistake and a swap of the axes in the latest version of the plotting code. This has now been fixed, and we left a note in our website changelog here: Website Changelog - Materials Project Documentation