Rhyolite-MELTS running with convergence issue

[Ri Cao]

Dear all,
I am a fresher user of Rhyolite-melt. Sorry for my interruption but I have a question regarding the Algorithm convergence issue.

Recently, when I run the MELTS software to do the fractional melting (I assume I should tick the ''fractionate liquid'' button in the Options list in order to run the fractional melting). However, if my system does not have SO3, the results just show me a piece of error information: The Quadratic minimization Algorhitms has failed to converge (see attached figure 1).

I understand from the previous users that I could change the chemical composition to make things work. On top of this, I modify the SO3 content from 0 to 1.6 wt% then the calculation works when SO3 > wt 1%. Would someone please provide some insights on why changing the SO3 content could make the calculation work? (i.e., some underlying physics)? Thank you very much and I look forward to your response.

Sincerely,