Running GMIN with MD move steps AMBER

Running GMIN with AMBER with MD move steps can be more efficient than with random cartesian move steps. To do so one needs the GMIN input file data, the AMBER file min.in for defining the energy function used whilst minimising, and the AMBER file min_md.inf or defining the energy function, parametrs for the MD move steps. The amber coordinate and topology files are also necessary, but will not be delt with here. These files are approximate.

GMIN input data file

 SLOPPYCONV  1.0D-2              
 TIGHTCONV   1.0D-3              
 UPDATES     8000                
 MAXERISE 0.001                  
 STEPS 100  1.0                  
 STEP  0.00 0.0      
 AMBER9 coords.inpcrd inpcrd          
 AMBERMDSTEPS                    
 MAXIT 10000 10000               
 MAXBFGS   1.0                   
 TEMPERATURE  1.0                
 RADIUS 300.0                    
 DUMPSTRUCTURES                 

GMIN AMBER minimisation min.in file

 # Minimisation Parameters
  &cntrl
   imin   = 1,
   ncyc = 1,
   maxcyc = 1,
   igb = 2, saltcon=0.2,
   ntb    = 0,
   cut    = 999.0,
   rgbmax = 25.0,
 /

For the minimisation, imin = 1, and no cutoffs cut = 999.0 should be used. Also igb=2 means that we are using the 2nd GB models is expected to perform well on proteins. saltcon=0.2 sets the surrounding (monovalent) salt concentration to 0.2 [mol/L]. ncyc = 1 perform 1 cycle of minimisation maxcyc = 1 perform 1 a maximum number of minimisation steps.

GMIN AMBER input min_md.in file

 # MD  Paramaters
  &cntrl
   imin   = 0,
   tempi = 700.0, temp0 = 700.0,
   ntt = 3, gamma_ln = 1.0,
   nstlim = 500, dt = 0.001,
   igb = 2, saltcon = 0.1,
   ntb    = 0,
   ntpr = 350, ntwx = 10,nrespa=1,
   cut    = 999.0,
   rgbmax=8.22,
 /