[CPMD-list] How to modify results more reasonable?

[Rongjian Sa]

Dear CPMD users,
I want to computer the binding energy of ammonium-benzene complex. It is well know 
this complex contains three stable structures (we denote them as 1, 2 and 3, 1 means one 
hydrogen atom of ammonium toward benzene, 2 means two hydrogen atoms of ammonium
toward benzene, 3 means three hydrogen atoms of ammonium toward benzene). Previous 
B3LYP and MP2 calculation using large basis sets shown 2 is most stable  and CPMD/70Ry
calculation also proven this. The calculated binding energy of 2 is also similar.  But for 1 and 3,
CPMD and Gaussian program give different results. In B3LYP and MP2 calculation, 3 is more 
stable than 1. While in CPMD calculation, 1 is more stable than 3.  Also in CPMD calculation, 
with the increasing of cell size, the deviation from experimental results increasing.  I have tried 
to increasing the convergence of optimization. But it seems little effect.  I wonder if you can 
give me some advice about my calculation. 
Input file of 1:

&CPMD
RESTART WAVEFUNCTION LATEST
OPTIMIZE  GEOMETRY
CONVERGENCE
1.D-5 5.D-5
 EMASS
 500
 MIRROR
&END
 &SYSTEM
  SYMMETRY
  1
  CELL
  15.1178 1.0 1.0  0  0  0
  CUTOFF
  70.0
  CHARGE
  1
&END
&ATOMS
*C_MT_GIA_BLYP  KLEINMAN-BYLANDER
LMAX=P
6
 0.0023  2.6441 -1.2327
 2.2960  1.3201 -1.2362
 2.2955 -1.3326 -1.2336
 0.0009 -2.6548 -1.2281
-2.2930 -1.3312 -1.2271
-2.2922  1.3216 -1.2297
*N_MT_GIA_BLYP   KLEINMAN-BYLANDER
   LMAX=P
 1
-0.0069  0.0238  4.7434
*H_MT_BLYP  KLEINMAN-BYLANDER
   LMAX=S
10
 0.0032  4.7040 -1.2833
 4.0772  2.3470 -1.2920
 4.0760 -2.3608 -1.2869
 0.0004 -4.7150 -1.2769
-4.0740 -2.3586 -1.2757
-4.0728  2.3496 -1.2809
-0.0029 -0.0039  2.7647
-1.6017  0.9524  5.3801
 1.5842  0.9530  5.3884
-0.0085 -1.8058  5.4252
&END
&DFT
  NEWCODE
  FUNCTIONAL BLYP
&END

Input file for 2:

 &ATOMS                               
 *C_MT_GIA_BLYP  KLEINMAN-BYLANDER    
 LMAX=P                               
 6                                    
  0.0001  2.6507 -1.1977              
 -0.0005 -2.6471 -1.1761              
 -2.2965  1.3281 -1.1968              
  2.2964  1.3277 -1.1951              
  2.2963 -1.3242 -1.1845              
 -2.2970 -1.3237 -1.1861              
                                      
 *N_MT_GIA_BLYP   KLEINMAN-BYLANDER   
    LMAX=P                            
  1                                   
 0.0008 -0.0084  4.6011               
                                      
 *H_MT_BLYP  KLEINMAN-BYLANDER        
    LMAX=S                            
 10                                   
  0.0003  4.7116 -1.2507              
 -0.0006 -4.7083 -1.2129              
 -4.0767  2.3580 -1.2364              
  4.0768  2.3573 -1.2334              
  4.0767 -2.3541 -1.2144              
 -4.0774 -2.3534 -1.2175              
 -0.0017  1.5778  3.4438              
  0.0049 -1.5530  3.3854              
 -1.5944 -0.0313  5.7201              
  1.5946 -0.0247  5.7222              
                                      
 &END                           
Input file for 3:
*C_MT_GIA_BLYP  KLEINMAN-BYLANDER  
LMAX=P                             
6                                  
 0.0000  1.2865  2.6672            
 2.2953  1.2470  1.3452            
 2.2956  1.1696 -1.3075            
 0.0000  1.1273 -2.6313            
-2.2956  1.1696 -1.3075            
-2.2953  1.2470  1.3452            
                                   
*N_MT_GIA_BLYP   KLEINMAN-BYLANDER 
   LMAX=P                          
 1                                 
0.0000 -4.6951 -0.0804             
                                   
*H_MT_BLYP  KLEINMAN-BYLANDER      
   LMAX=S                          
10                                 
 0.0000  1.4037  4.7256            
 4.0760  1.3412  2.3727            
 4.0774  1.1969 -2.3365            
 0.0000  1.1327 -4.6935            
-4.0774  1.1969 -2.3365            
-4.0760  1.3412  2.3727            
 0.0000 -6.6392 -0.2002            
-1.5821 -4.0530  0.8709            
 1.5821 -4.0530  0.8709            
 0.0000 -3.8717 -1.8560         
&END                               
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