# 29.10.2019 Karen Fidanyan
This regtest deals with geometry optimization with fixed atoms.

1.  Geometry optimization test: 1 water molecule in vacuum
    with different numbers of freezed atoms.

    resulting files are 
    sim-[0-2]fixed.<mode>.out - contains energies at each optimizaton step
    sim-[0-2]fixed.<mode>.pos_0.xyz

    0-2 means the number of atoms fixed in a water molecule.
        0 and 1 are expected to give the same energy, 
        2 should give higher energy.

2.  'far-away' test gives the comparison of optimization with and without constraints 
    for the system, where constraint doesn't matter: 
    1 very distant atom (far beyond the interaction range) in addition to distorted water molecule.
    Here relaxation WITH and WITHOUT fixatom should give equal result and completely equal relaxation trajectory.

RESULTS:
All optimizers pass this test successfully and give the same energies and structures (wrt defined tolerances).
But CG and SD have HUGE problems with convergence. It is unrelated to fixatoms.

#         Energy-0-fixed  Energy-1-fixed  Energy-2-fixed  Force calls
BFGS            -0.00384        -0.00381      0.05363918           22
LBFGS           -0.00384        -0.00381      0.05363917           15
BFGSTRM         -0.00384        -0.00381      0.05363918           16
CG              -0.00384        -0.00381      0.05363918          434
SD              -0.00384        -0.00381      0.05363916         1107
