Constraining a dihedral angle to retain it's current value during optimization

[liz.deco...@gmail.com]

Hello all,

I can't tell if I'm encountering a bug, or just setting up my mpr file wrong. I'd like to optimize a structure while holding a specific dihedral angle constant.

My (very simplified, with small basis sets for speed) input looks like:

``` memory,1685,M,GA=0,M

 gdirect

 basis=vdz

 symmetry,nosym

 orient,noorient

 geomtyp=xyz

 geometry={

 12

 Cartesian coordinates in Angstrom units

 C1 0.00043300 0.10763800 1.94260700

 N2 -0.00131100 0.63644800 0.60164800

 C3 -0.00009200 -0.17607200 -0.48074500

 O4 -0.00031400 -1.38426900 -0.38407700

 C5 0.00017800 0.52829600 -1.82029800

 H6 -0.87211100 -0.51959200 2.12602300

 H7 -0.01679700 0.93565600 2.64723500

 H8 0.88974500 -0.49260700 2.13696400

 H9 0.00446000 1.63077300 0.47296500

 H10 0.00563100 1.61602700 -1.75576300

 H11 -0.87880300 0.22293200 -2.38652100

 H12 0.87309500 0.21405900 -2.39091500

 }

 core,5

 set,charge=0

 {df-hf,accu=15,maxit=50,use_disk}

 {df-mp2}

 {optg,method=slrf,maxit=100,root=1,savexyz=run.xyz

 hessian,model=vdw

 prim,d1,dihedral,atoms=[1,2,3,4]

 fix,d1

 }```

The job gets as far as finishing the df-mp2 calculation, then hangs.

Is this the correct way to specify "please optimize my structure while holding this dihedral constant"? (If it is, I'll gather more info and file a proper bug report. But I'm hoping that the issue is in my input formatting, not in the code).

[dolg...@gmail.com]

Hi, 

you might have used:

...

constraint,0.158,deg,dihedral,atoms=[C1,N2,C3,O4]
...

instead of

...

prim,d1,dihedral,atoms=[1,2,3,4]

 fix,d1

...

Best,

Greg