Determine the correct capacitors value
From AVR042, &quot;AVR Hardware Design Considerations&quot;, section 4, &quot;Using crystal and ceramic resonators&quot;, subsection 2, &quot;General about crystals and ceramic resonators&quot;:

\$C = 2 ⋅ C_L − C_S\$
(CS can be estimated to be 5pF - 10pF)

So, about 30pF.