From: FyD via AMBER <amber.ambermd.org>
Date: Wed, 01 Jul 2026 10:01:15 +0200
Dear All,
I do not understand the energy values reported for '3-point' angles in
triple bonds by sander 2024 (automatic by REDServer Dev./PyRED)|pmemd
2024; done manually on the q4md-fft and MatriCS
https://www.matrics.u-picardie.fr/amber/ clusters):
For HF/6-31G(d) optimized ethyne H-C≡C-H (simple model), there are 2
angles HCC & CCH, and measured_angle_values ~ parm10 eq. value ~ 180
deg.; so the corresponding angle energy values ~ 0 kcal/mol:
sander|pmemd do not find '0'...
Similar 'results' are found for propyne and acetonitrile, and
discrepancies are observed between PyRED and sander for '3-point'
angles with triple bonds...
[xxxx.master P2875]# grep ANGLE dE_sander-vs-PyRED_SinglePointEnergyValues.log
ANGLE sander vs PyRED single-point energy abs(differences) =
.2000 [WARNING] i.e. C≡C_Ethyne
ANGLE sander vs PyRED single-point energy abs(differences) =
.2600 [WARNING] i.e. CC≡C_Propyne
ANGLE sander vs PyRED single-point energy abs(differences) =
.1600 [WARNING] i.e. CC≡N_Acetonitrile
ANGLE sander vs PyRED single-point energy abs(differences) =
0 [OK] i.e. C≈C_Toluene
Do I miss something?
Thank you
Best Francois
See data below:
WARNING: a job is kept _only_ 5 days on the public account...
BOND = 0.2542 ANGLE = 0.2000 DIHED = 0.0000
VDWAALS = 0.0000 EEL = 0.0000 HBOND = 0.0000
1-4 VDW = -0.0055 1-4 EEL = 7.2098 RESTRAINT = 0.0000
!!! ANGLE = 0.2000 !!!
[xxxx.master P2875]# cat Project.config
#_______Keyword(s) added in the Project.config file by the user before
the input submission procedure:
MOLECULE1-TITLE = C≡C_Ethyne
MOLECULE2-TITLE = CC≡C_Propyne
MOLECULE3-TITLE = CC≡N_Acetonitrile
MOLECULE4-TITLE = C≈C_Toluene
