IRCCAR: Difference between revisions

Revision as of 07:52, 11 July 2025

The IRCCAR file defines a discretized transformation path. Usually this is taken from an intrinsic reaction coordinate (IRC - using IBRION=40), projected onto a small set of internal coordinates. It is required to define the path-based coordinates IS and IZ in ICONST.

However, this IRC is followed during a biased molecular dynamics (MD) simulation, similar to the Blue moon ensemble method. The structure of the file is:

M
chi_1(1) chi_2(1) ... chi(r)(1)
chi_1(2) chi_2(2) ... chi(r)(2)
...
chi_1(M) chi_2(M) ... chi(r)(M)

where M is the number of points in the file and chi_j(i) is [math]\displaystyle{ \tilde{\chi}_k(i) }[/math], the discretized transformation path in terms of internal coordinates.

[math]\displaystyle{ \tilde{\chi}_k(i) }[/math] can take values between 0 and 1.

For further information, see pages 50-51 of "Investigating chemical reactions with VASP" .

@@ Line 2: / Line 2: @@
-However, this IRC is followed during a biased molecular dynamics (MD) simulation, similar to the [[Blue moon ensemble]] method. The Structure of the file is:
+However, this IRC is followed during a biased molecular dynamics (MD) simulation, similar to the [[Blue moon ensemble]] method. The structure of the file is:
-  N
+  M
-  a1 b1
+ chi_1(1) chi_2(1) ... chi(r)(1)
-  a2 b2
+ chi_1(2) chi_2(2) ... chi(r)(2)
-  a3 b3
+ ...
-  ...
+ chi_1(M) chi_2(M) ... chi(r)(M)
-  aN bN
-where N is the number of points in the file, a<sub>i</sub> is the first basis???, b<sub>i</sub> is the second basis.
+where <code>M</code> is the number of points in the file and <code>chi_j(i)</code> is <math>\tilde{\chi}_k(i)</math>, the discretized transformation path in terms of internal coordinates.
-There is a guide on how to use this tag in the How-to ADD LINK.
+<math>\tilde{\chi}_k(i)</math> can take values between 0 and 1.
+For further information, see pages 50-51 of "Investigating chemical reactions with VASP" {{Cite|bucko:2025}}.
 <!--[[Category:Files]][[Category:Input files]][[Category:Advanced molecular-dynamics sampling]][[Category:Biased molecular dynamics]][[Category:Transition states]]-->