I adjusted the equilibrium constant, but the result does not show the Cs+

[duanjiabin]

I adjusted the equilibrium constant, but the result does not show the Cs+.
SOLUTION 1
    temp      25
    pH        7
    pe        4
    redox     pe
    units     mmol/kgw
    density   1
    -water    1 # kg

PHASES
Cs2O
    H2O + 2Cs+ = Cs2O + 2H+
    log_k     -89.96
    delta_h   511.91 kJ

REACTION 1
    Cs2O       1
    1 moles in 1 steps

SOLUTION_MASTER_SPECIES
    Cs            Cs+              0     132.9054        132.9054

SOLUTION_SPECIES
Cs+ = Cs+
    log_k     0
H2O + 2Cs+ = Cs2O + 2H+
    log_k     -89.68
    delta_h   511.91 kJ

[dlparkhurst]

You have not defined any Cs in your solution. Add Cs in SOLUTION, or add Cs2O in EQUILIBRIUM_PHASES.

You PHASES definition is wrong. The mineral formula should be the first item on the left-hand-side of the equation. Cs2O is not a likely mineral phase for most systems.

[duanjiabin]

Thank you very much for your reply, I have modified it successfully!