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Syntax

 DCSA {<Chem-Shift-Anis-statement>} END 
 <DCSAnisotropy-statement>:== 
  ASSIgn <selection> <selection> <selection> <selection> 
  <selection> <selection> <selection> 
  <real> <real> <real>
  {* atom i atom j atom k atom l 
   ! atom m atom n atom o 
   ! CSA-obs  CSA-err-min CSA-err-plus *}
  {* atom i = center, atom j = Z, atom k = X, atom l = Y *}
  {* if TYPE=PHOS atom m define the phosphorus atom *}
  {* atom n and o define the o1p and o2p *}
  {* if TYPE=CARB atom m define the carbonyl atom *}
  {* atom n and o define the oxygen and nitrogen(i+1) *}
  {* if TYPE=NITR atom m define the carbonyl atom (i-1) *}
  {* atom n and o define the nitrogen and NH *}
  {* The unit for CSA in the constraint file is ppb *}
  CLASsification <name> ! Starts a new class. Applies to all 
       ! ASSIgn , TYPE, and FORCe entries until 
       ! another CLASS entry is issued. 
  SCALe <real> for normalizing the alignment tensor
  {* Use the static dipolar coupling (in Hz) for the nuclei 
   ! used to calculate Da 
   ! DNH(r=1.04A) = 21652.1 ; DCH (r=1.08A) = 47965.1 *}
  TYPE <PHOS | CARB | NITR> ! type of CSA
  COEFficient <real> <real> <real>
  coef: <DFS> <Da in Hz> <rhombicity>
  SIGMa <real> <real> <real>
  sigma <s11> <s22> <s33> in ppm
       ! for 15N -108.5 45.7 62.8 
       ! for 13C' -74.7 -11.8 86.5 
       ! for 31P in nucleic acids 19.67 -99.33 79.67 
  FORCeconstant <real> ! force constant for all 
       ! assignments in the current class. {default = 50} 
  NREStraints <integer> ! number of slots for CSAnisotropy 
       ! restraints to allocate in memory {default = 200} 
  POTEntial <SQUAre | HARMonic> ! whether to use CSA-err or not
  PRINt THREshold <real> ! prints CSAnisotropy violations 
       ! greater than the specified value 
  RESEt  ! erases the CSA. assignment table, but keeps 
       ! NREStraints the same.
Xplor-NIH 2025-03-21