[Pw_forum] How to compare total energy calculation results with references?

[Tengfei Luo]

Dear all:
I'm new to PWscf. I tried the first example which includes the total energy calculation of Si. The result I got from this example was: 

!    total energy              =   -15.84452726 Ry

I believe this is for the total energy of the two Si atoms system. However, from the reference data here:

http://physics.nist.gov/PhysRefData/DFTdata/Tables/14Si.html

The total energy is -288.198397 a.u.. The caluclated data is very different from this. Is this because of using of pesudopotential? How can I get the real totoal energy? 

I would appreciate any help!

Thank you!

Tengfei
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