electron density is converged when the relative difference between dense.EdenTrue and phycon.eden 
is less than conv.EdenErrorAllowed - the error allowed is reset with the set eden error command.

lgConvEden() returns true when electron density is converged

conv.lgConvEden is true when electron density is converged

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current electron density is phycon.eden 

true electron density is dense.EdenTrue as set in eden_sum (contained in ConvIonizeOpacityDo)

ConvEdenIoniz converges the electron density

