How to Resolve Convergence Failures in Gaussian NH3+ Calculations?

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Homework Statement


I am using gaussian to calculate the potential energy surface for NH3+, but I have been having troubles with convergence failures. I did some searching on the internet and found that using SCF=qc can sometimes help with convergence failures since it instruct the program to have less strict criteria. So here's what I entered:

Route Section: #MP2 cc-PVDZ SCF=qc Scan Pop=Reg Guess=INDO

Title: Ammonia Cation Scan

Charge, Multiplicity: 1 2

N
X 1 1.0
H 1 nh 2 xnh
H 1 nh 2 xnh 3 120.0
H 1 nh 2 xnh 3 -120.0

nh 0.5 60 .04
xnh 29.0 60 1.0

And the scan failed after about 2 hrs. and 44 min. I looked at the output file, and it said that the error was due to the curvature, and I'm not quite sure what that means. Any suggestions?


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The Attempt at a Solution

 
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Anyone? Is this maybe due to the fact that NH3+ is planar?