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Syntax
PCSA {<Pseuso-Chem-Shift-Anis-statement>} END
<PCSAnisotropy-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
! PCSA-obs PCSA-err-min PCSA-err-plus *}
{* atom i = center, atom j = Z, atom k = X, atom l = Y *}
{* atom m defines the central atom *}
{* atoms n and o define the at1 and at2 *}
{* The unit for PCSA 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 *}
COEFficient <real> <real> <real>
coef: <DFS> <Da in Hz> <rhombicity>
SIGMa <real> <real> <real>
CSA sigma <d11> <d22> <d33> <theta>
CSA tensor in ppm for A-form RNA or B-form DNA base carbons
d33 is orthogonal to the base plane
theta is the angle in degrees between d11 and heavy atom bisector
! d11 d22 d33 theta
! for C2:A DNA/RNA 89.0 15.0 -104.0 -2.0
! for C5:C/U DNA/RNA 82.0 2.0 -85.0 -5.0
! for C6:C DNA 96.0 19.0 -115.0 28.0
! for C6:T DNA 97.0 -1.0 -96.0 29.0
! for C6:C/U RNA 125.0 -7.0 -119.0 29.0
! for C8:A DNA/RNA 74.0 5.0 -79.0 32.0
! for C8:A DNA/RNA 80.0 5.0 -85.0 32.0
FORCeconstant <real> ! force constant for all
! assignments in the current class. {default = 0.010}
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