Table 2 The table shows the enthalpy change (ΔH) (eV/atom) of molecular compounds in liquid metallic hydrogen, compared with reference states for carbon, oxygen, and nitrogen, at 500 GPa

From: Hydrogenation of saturated organic and inorganic molecules in metallic hydrogen

References

Enthalpy (eV/atom)

Compounds

Enthalpy (eV/atom)

Δ H (eV)

H128

−9.630(1)

CH6 in CH276

−10.116(1)

−0.16 ± 0.38

C54

−144.087(2)

C2H8 in C2H576

−10.096(1)

−0.30 ± 0.60

O48

−420.655(2)

C3H10 in C3H576

−10.326(1)

0.53 ± 0.62

N64

−260.457(4)

CH4OH in COH124

−14.007(1)

−5.99 ± 0.15

  

OH3 in OH124

−12.977(1)

−7.39 ± 0.14

  

NH4 in NH124

−11.665(1)

−3.60 ± 0.15

  1. For carbon at 500 GPa, the reference state is diamond. For oxygen, we use the C2/m space group structure157 which is the most stable form from 100 to 250 GPa. For nitrogen, we use the helical tunnel structure of the P212121 space group reported stable above 320 GPa158. Our calculations imply complete solubility of carbon, oxygen and nitrogen.
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