[Pw_forum] ev.x gives wrong results

[anyy zsj]

Dear all:
I use the ev.x to fit my equation of state but get several results that
doesn't match. Below is an example:
   1.4989396432   -6.0466776328
   1.5430233198   -6.0795705718
   1.5879629631   -6.0993455319
   1.6804430727   -5.9859764266
The first column is volume and the second energy with Ry. After ev.x I
input Ang, noncubic, 4, it gives me a results of 0.40 for minimal volume.
It is certainly wrong.

Aother example for the below data:
10.1      -48.570860572794118
10.3      -49.368013045588235
10.5      -49.714550792647060
10.7      -49.667482497058820
10.9      -49.305953287500003
The first column is lattice constant with angstrom and the second energy
with Ry. After ev.x I input Ang, sc, 4, it gives me 10.50369, while I get a
different value 10.57517 by fitting to the formula in PRB 28,5480 (1983)
of Murnaghan's equation.:
http://gilgamesh.cheme.cmu.edu/doc/software/jacapo/appendices/appendix-eos.html
I have tested many groups of data but the discrepancy is there for those
large lattice parameters. Does ev.x use another equation or something else
I have missing? Thank you very much.
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