[Pw_forum] relaxation: mistake in finding the lowest energy structure

[ZARA NBSH]

Dear all,
I would like to study the interaction between 2 organic molecules (contains
O, H, and C atoms).
As the first step I relax
​ed​
the structure
​

​(​
using
​ calculation = 'relax' in &control)
.
​M​
y problem is that after finishing the run, it could not find the lowest
energy s
​tructure
.
And I could
​ find some new structures (by hand) with​
 lower
​energies
.
The
​energy ​
difference
​,
​ ~
10
​0​
meV
​,​
 is
​strongly higher​
 than the accuracy of energy
​ in my calculations​; and also the structures are very different.

In my calculation, the​
 vacuum
​ is large enough​ and forc_conv_thr is 1.0D-5.

My question is how can I find the lowest energy
​structure
?

Bests,
​zara
​
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