Dear Bruce D.Ray...<br><br>I had used the TPO parameters as u gave in previous posts.<br><br><br><span>[
<b style="color: black; background-color: rgb(255, 255, 102);">TPO</b> ]</span><br><span> [
atoms ]</span><br><span>    
N    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_238   -0.500     1</span><br><span>    
H    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_241    0.300     1</span><br><span>   
CA    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_224B   0.140     1</span><br><span>   
HA    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_140    0.060     1</span><br><span>   
CB    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_158    0.205     2</span><br><span>   
HB    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_140    0.060     2</span><br><span>  
OG1    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_447   -0.700     2</span><br><span>    
P    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_445    1.795     3</span><br><span>  
O1P    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_446   -1.120     3</span><br><span>  
O2P    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_446   -1.120     3</span><br><span>  
O3P    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_446   -1.120     3</span><br><span>  
CG2    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_135   -0.180     4</span><br><span> 
HG21    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_140    0.060     4</span><br><span> 
HG22    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_140    0.060     4</span><br><span> 
HG23    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_140    0.060     4</span><br><span>    
C    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_235    0.500     5</span><br><span>    
O    <b style="color: black; background-color: rgb(255, 255, 102);">opls</b>_236   -0.500     5</span><br><span> [
bonds ]</span><br><span>    
N     H</span><br><span>    
N    CA</span><br><span>   
CA    HA</span><br><span>   
CA    CB</span><br><span>   
CA     C</span><br><span>   
CB    HB</span><br><span>   
CB   OG1</span><br><span>   
CB   CG2</span><br><span>  
OG1     P</span><br><span>  
O1P     P</span><br><span>  
O2P     P</span><br><span>  
O3P     P</span><br><span>  
CG2  HG21</span><br><span>  
CG2  HG22</span><br><span>  
CG2  HG23</span><br><span>    
C     O</span><br><span>   
-C     N</span><br><span> [
dihedrals ] ; override some of the typebased dihedrals</span><br><span>    
N    CA    CB   OG1    dih_SER_THR_chi1_N_C_C_O</span><br><span>    
C    CA    CB   OG1    dih_SER_THR_chi1_CO_C_C_O</span><br><span>   
CA    CB   OG1   HG1    dih_SER_THR_chi2_C_C_OH_HO</span><br><span> [
impropers ]</span><br><span>   
-C    CA     N     H    improper_Z_N_X_Y </span><br><span>   
CA    +N     C     O    improper_O_C_X_Y </span><br clear="all"><br><br>And i added Ryckaert-Belleman dihedrals in ffoplsaabon.itp file basing on the errors  got after i run pdb2gmx command.<br><br>And i had left the 6 coefficients (c0 to c5) as 0.0000 because i dunno how to derive those values.<br>
<br>So please help me how to fill those values. I had gone through the RB dihedrals main article but im not clear.<br><br>Just give me sugggestions to derive those values and if u have those values it would me much more easier for me....:-)<br>
<br>Thank you in advance<br>sumanth<br><br><br>-- <br><b style="font-family: courier new,monospace;">SUMANTH KUMAR.M</b><br style="font-family: courier new,monospace;"><span style="font-family: courier new,monospace;"></span><br>