Problem with vcs_equilibrate('HP')

There seems to be something wrong with the vcs_equilibrate('HP') function, when 
the solver is not explicitly defined as solver=1. 

What steps will reproduce the problem?
1. Define a phase 'gas' as an ideal gas
2. Define a mixture containing this gas: mix=Mixture([gas])
3. Use the mix.vcs_equilibrate('HP') method

What is the expected output? What do you see instead?
I do not expect the enthalpy of the gas to vary when invoking 
mix.vcs_equilibrate('HP'). Nevertheless, when calling 
mix.vcs_equilibrate('HP'), the enthalpy of the gas is changed dramatically. 

Interestingly, this issue is not encountered when using 
mix.vcs_equilibrate('HP', solver=1).

This is shown in the attached example. The script requires h2o2.cti, 
distributed with Cantera.

What version of the product are you using? On what operating system?
I encountered this behavior on:
1. 32-bit Windows, Python 2.7.2, Cantera 2.0.0 installed with the binary 
installers
2. 64-bit Linux, Python 2.7.3, Cantera SVN r1878

Original issue reported on code.google.com by chdoi...@gmail.com on 12 Oct 2012 at 3:24

Attachments:

minimal.py

hkmoffat / cantera

Problem with vcs_equilibrate('HP') #122