How to Resolve Convergence Failures in Gaussian NH3+ Calculations?

[bcjochim07]

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?

Homework Equations

The Attempt at a Solution

 

[bcjochim07]

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