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<body class='hmmessage'><div dir='ltr'>Hey, everyone,<br><br>I'm working on the vertical transition energy in two ways:<br><br>1. a state-averaged CASSCF calculation of all states in one calculation (i also tried to include different numbers of states, and the result may vary significantly with the number of state!!)<br>2. CASSCF calculations of ground state and excited states individually<br><br>it turns out that the transition energies are very different from the above ways, and they could differ as large as 1 eV. Moreover, including 10 states and 20 states in a state-averaged CASSCF calculation also lead to very different results.<br><br>I don't know whether this ever occurs to any of you. If so, are there any reasons or explanations for this? Which is the most reliable way to calculate the energy?<br><br>Thanks in advance!<br><br>Qinghua<br><br><br> </div></body>
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